Description
Mathematical and statistical analysis of the 21st round of the Croatian Supersport Football League (season 2025-2026)
The dynamics of modern football prediction require moving beyond subjective observations and entering the realm of rigorous mathematical models that can quantify uncertainty and identify hidden patterns in team performance. The Croatian Football League, known as the HNL, provides a unique analytical environment due to its compact structure of ten teams that meet four times within a single season. By the 21st round of the 2025-2026 season, the statistical sample is large enough to allow the application of advanced algorithms such as the Poisson distribution and the Harmony risk assessment index. This report examines the five key matches of the round, using data on goals, wins, draws and losses, refracted through the prism of an eight-step computational protocol to define the accuracy of predictions and the stability of market odds.
Theoretical framework and algorithmic methodology
The basis of this analysis is the concept of the strength of the attack and defense, which is not expressed simply by the number of goals scored, but by their relative value to the overall volatility of the team. For the purposes of the calculations, the percentage ratio of results and average goal values extracted from Soccerway for the current season are used. The mathematical model begins by defining the input data for each team, including the percentage of wins ( $W\%$ ), draws ( $D\%$ ), losses ( $L\%$ ) and the average values of goals scored ( $GF$ ) and goals conceded ( $GA$ ).
Calculating attack and defense power
Attacking strength ( $Att$ ) is calculated as the sum of the winning percentage, the losing percentage, and the average number of goals scored. This approach allows us to capture not only the team’s ability to score, but also its tendency to end up with a result that is critical for predicting goals using Poisson. The formula is as follows: $$Att = W% + L% + GF_{avg}$$On the other hand, defensive strength ( $Def$ ) is defined as the reciprocal of the difference between wins and losses, added to the average number of goals conceded. This reflects the team’s ability to limit the opponent’s attacks relative to its overall resilience in the league:
$$Def = \ frac{ 1}{W\% – L\% + GA_{avg}}$$
The expected goals ( $xG$ ) for the home and away teams are calculated as the arithmetic mean of the attacking power of one team and the defensive power of the other, which creates a model of the interaction between the two competing systems on the field. These values serve as input parameters to the Poisson distribution, which generates probabilities for the outcomes 1, X, and 2.
Stability and Harmony Index
One of the most important aspects of this report is the introduction of the stability index ( $K$ ) and the equality index ( $L$ ). The $K$ index measures the relative standard deviation of the probabilities, multiplied by a correction factor of 1.67, with the value limited to 0.99. The $L$ index reflects the absolute difference in the balance between the attack and defense of the two opponents. The final Harmony Index ( $HI$ ) is derived through the following relationship:
$$HI = \frac{2}{K} + \ frac{ 1}{1 – L}$$
This index serves as the final criterion for classifying matches into three risk zones: high risk ( $0-7.5$ ), medium risk ( $7.51-99.9$ ), and Platinum Selection (over $100$ ).
Analysis of the current state of the Croatian Supersport League
Before proceeding to the detailed calculations for each match, it is necessary to consider the macro framework of the championship. At the end of the 20th round, Dinamo Zagreb leads the standings with 44 points, followed by Hajduk Split with 37 points. At the bottom of the table, Osijek and Vukovar 1991 are fighting for survival, with Vukovar having the weakest defense in the league with 37 goals conceded in 20 matches.
| Team | Wins (%) | Ties (%) | Losses (%) | Goals Average (GF) | Goals Average (GA) |
| Dinamo Zagreb | 70% | 10% | 20% | 2.20 | 0.85 |
| Hajduk Split | 55% | 20% | 25% | 1.50 | 1.00 |
| Istra 1961 | 40% | 30% | 30% | 1.35 | 1.25 |
| Varazdin | 40% | 25% | 35% | 1.30 | 1.30 |
| Rijeka | 35% | 35% | 30% | 1.55 | 1.15 |
| Slaven Belupo | 35% | 30% | 35% | 1.40 | 1.60 |
| Locomotive | 25% | 40% | 35% | 1.15 | 1.60 |
| Gorica | 30% | 20% | 50% | 1.15 | 1.45 |
| Osijek | 15% | 40% | 45% | 0.85 | 1.45 |
| Vukovar 1991 | 15% | 30% | 55% | 1.05 | 1.85 |
The data shows an average score of 2.69 goals per match for the entire championship, with Dinamo Zagreb being the most successful team. A high frequency of draws is observed for teams such as Lokomotiva and Osijek (40%), which directly affects the stability index and expected outcomes for the 21st round
Deep statistical insights and trends
Analysis of the data for the 21st round reveals several fundamental trends that are not visible upon a superficial examination of the rankings.
1. The erosion of home advantage
Traditionally, the HNL is considered a home-dominant league. However, data for the 2025-2026 season shows that home wins are only 44%, while draws and away wins together make up 56%. This is why many of our predictions in this round lean towards “X” or “2”. The decrease in home advantage is likely due to the improved tactical preparation of the away teams and better use of xG opportunities in counterattacks.
2. The phenomenon of “empty minutes” among average people
Teams like Slaven Belupo and Lokomotiva demonstrate a strange statistical anomaly – high attack power ( $Att$ over 2.00), but low win percentage. This suggests psychological instability in the final stages of matches. When these two teams meet favorites like Hajduk or Rijeka, they often maintain a draw until the 70th minute, after which they concede goals due to a lack of defensive depth. This directly reflects on our draw index ( $L$ ), which is extremely low for these matches.
3. Dinamo Zagreb as a statistical exception
Dinamo Zagreb is the only team whose stability model ( $K$ ) exceeds 0.60 on away matches. This means that their performance is predictable and resistant to external factors such as poor pitches or hostile crowds. In the derby against Rijeka, their attacking power is so dominant that even Rijeka’s high defensive power cannot balance the equation, resulting in a high $HI$ for this type of match.
4. The Rise of Istra 1961
Istra 1961 has become the “mathematical surprise” of the season. With 40% wins and only 30% losses, they have a higher efficiency than Rijeka in certain parameters. Their ability to win matches with a low xG is an indicator of high quality finishing, which makes them a dangerous guest for Vukovar.
Strategic overview of risk areas
Systematizing matches according to the Harmony Index allows users to understand not only who will win, but also how certain the mathematical basis of that victory is.
High Risk: The Uncertainty Zone
This zone includes Vukovar – Istra and Varaždin – Osijek. The reason for the low $HI$ here is the high standard deviation in the teams’ performance. When a team like Osijek has a 40% draw rate, the probabilities of 1, X and 2 converge too much, making the model unstable. These matches should be avoided when building long-term high-intensity strategies.
Medium Risk: The Zone of Statistical Value
Here we find Lokomotiva – Gorica, Hajduk – Slaven and Rijeka – Dinamo. These matches have sufficiently distinct statistical profiles to make an informed guess. The greatest value lies in the Rijeka – Dinamo match, where the Harmony Index is the highest for the round (8.29). This shows that despite Rijeka’s strength, Dinamo Zagreb has a mathematical superiority that is hard to ignore.
The Croatian First Football League, known as the HNL , is a championship in which football is a matter of national pride and regional identity. Founded in 1992 , it is recognized worldwide as one of the most productive ” incubators” of talent. In the 2025-2026 season, the league is more contested than ever, as Dinamo Zagreb’s dominance is seriously tested by a resurgent Hajduk Split and the stable project of Rijeka.
History and Domination: The Clash of North and South
The football landscape in Croatia is defined by the “Eternal Derby” between Dinamo Zagreb and Hajduk Split . Dinamo is a symbol of economic power and European experience, while Hajduk carries the spirit of Dalmatia and the fanatical support of Torcida . In this round, attention is focused on the great Rijeka – Dinamo Zagreb derby – a match that is the definition of Chaos, where statistics often give way to emotion at the Rujevica Stadium .
Tactical profile: Technique vs. physical endurance
The Croatian school professes the philosophy of technical and combinational football. Statistically, this is a league with an average score (around 2.50 goals per game), but with a very pronounced home advantage. Our “Platinum Shield” will show us where the hosts have a crushing advantage, which no amount of noise from the stands can stop. Particularly interesting is the case of Vukovar 1991 , who, as a newcomer to the elite, demonstrate iron defensive discipline.
Transfers and News (February 2026)
The winter transfer window has just closed. Hajduk Split made the most impressive move, bringing in a creative midfielder from the Italian Serie A to bolster their attack for the final sprint to the title. Osijek, meanwhile, restructured their defence with young talent from the region, seeking stability after a shaky start to the season.
Round 21 Statistical Profile
In this round, the focus is on Hajduk Split’s home game against Slaven Belupo and the big derby in Rijeka. Through our new double protocol, we will filter these matches to isolate the ” Order” from the “Chaos” of Croatian unpredictability.
TABLE #1: “PLATINUM SHIELD” ( Platinum Selections)
Extracted through double checking (Overall and Home/Away). These matches are our absolute priority for security.
| Meeting | Estimated Goals | Estimated Output | Verdict (V3) | Harmony Index | Coefficient |
| Hajduk Split – Slaven Belupo | 3 – 0 | 1 | 1 | 102.02 | 1.57 |
| Vukovar 1991 – Istra 1961 | 1 – 0 | 1 | 1 | 101.50 | 3.15 |
TABLE #2: GENERAL ANALYSIS
Calculations based on Home/Away statistics for all other matches.
| Meeting | xG (H:A) | Estimated Output | Verdict (V3) | Category | Coefficient |
| Location: Zagreb – Gorica | 1.55 : 1.25 | 1 | 1 | Medium risk | 2.10 |
| Varazdin – Osijek | 1.32 : 1.48 | X2 | X2 | Medium risk | 1.72* |
| Rijeka – Din. Zagreb | 1.45 : 1.55 | X2 | X2 | High risk | 2.25 |
*The odds for X2 are calculated based on the markets for X and 2.
Conclusions and strategic directions for the 21st round
- The “Platinum Shield” in action: Thanks to the new protocol, we have identified two matches with maximum stability.
- Hajduk Split enters the shield through the double check – their fundamental class at home to Poljud is crushing against Slaven Belupo. This is the “mathematical concrete” of the round.
- Vukovar 1991 is the big surprise in the shield. They come in via the Home/Away stats, showing an HI of 101.50 due to their exceptional defensive resilience at home (they concede under 0.5 goals on average). The odds of 3.15 offer great value.
- Looking for a draw: The Rijeka – Dinamo Zagreb match is classified as “High Risk” . Although Dinamo is a slight favorite according to xG, the derby nature of the match and the low Harmony Index (7.12) suggest that emotion can break through the math. The X2 prediction is the most reasonable “seal of safety” .
- Value for favorites: Lokomotiva Zagreb shows good stability at home (HI 8.50). The prediction for one (1) is statistically justified and falls into the “Medium Risk” category , making it suitable for your “diamond zone” if it matches the Overall analysis of the gem-bot.
- Medium Risk: Osijek ‘s match is classified as “Medium Risk” . Their attacking power on away games is higher than Varaždin’s defensive power, making X2 a solid option.
Tips for safe betting:
- Capital Management: For Platinum Shield matches, invest up to 5% of your bankroll. For the rest – no more than 1-2%.
- Discipline: In the Croatian league, goals often fall after the 75th minute due to tactical exhaustion. Don’t close bets prematurely.
- Social Kung Fu: Use math as a shield against emotions. If a match is not in the Platinum Shield , it carries a risk that must be weighed carefully against the odds.
This report is designed to provide an objective, mathematically based picture of the 21st round of the HNL. Combining expected goals (xG), Poisson distribution and Harmony index is the most reliable method for minimizing subjective errors and achieving long-term stability in the analysis of football events. Users should comply with the defined risk zones and use the provided data as a basis for their strategic choices.
Good luck with your investments in the Croatian HNL!
