| Kostas21 vs Jin | 57–50 | 53.27% |
| Kostas21 vs Hwoarang | 57–38 | 60.00% |
| Kostas21 vs Heihachi | 40–54 | 42.55% |
| Kostas21 vs King | 50–41 | 54.95% |
| Kostas21 vs Kazuya | 41–48 | 46.07% |
| Kostas21 vs Reina | 52–23 | 69.33% |
| Kostas21 vs Bryan | 28–38 | 42.42% |
| Kostas21 vs Law | 33–25 | 56.90% |
| Kostas21 vs Lili | 22–27 | 44.90% |
| Kostas21 vs Eddy | 17–31 | 35.42% |
| Kostas21 vs Paul | 25–19 | 56.82% |
| Kostas21 vs Clive | 22–21 | 51.16% |
| Kostas21 vs Dragunov | 23–18 | 56.10% |
| Kostas21 vs Steve | 21–18 | 53.85% |
| Kostas21 vs Devil Jin | 17–20 | 45.95% |
| Kostas21 vs Yoshimitsu | 18–17 | 51.43% |
| Kostas21 vs Jun | 16–19 | 45.71% |
| Kostas21 vs Asuka | 25–9 | 73.53% |
| Kostas21 vs Nina | 21–13 | 61.76% |
| Kostas21 vs Azucena | 18–15 | 54.55% |
| Kostas21 vs Lars | 15–14 | 51.72% |
| Kostas21 vs Feng | 15–9 | 62.50% |
| Kostas21 vs Victor | 11–13 | 45.83% |
| Kostas21 vs Jack-8 | 13–10 | 56.52% |
| Kostas21 vs Xiaoyu | 13–8 | 61.90% |
| Kostas21 vs Lidia | 12–8 | 60.00% |
| Kostas21 vs Kuma | 8–10 | 44.44% |
| Kostas21 vs Raven | 6–12 | 33.33% |
| Kostas21 vs Anna | 11–7 | 61.11% |
| Kostas21 vs Alisa | 9–7 | 56.25% |
| Kostas21 vs Claudio | 9–6 | 60.00% |
| Kostas21 vs Lee | 5–8 | 38.46% |
| Kostas21 vs Panda | 5–6 | 45.45% |
| Kostas21 vs Leo | 4–3 | 57.14% |
| Kostas21 vs Zafina | 4–3 | 57.14% |
| Kostas21 vs Leroy | 4–2 | 66.67% |
| Kostas21 vs Shaheen | 3–1 | 75.00% |
Limitations
This data is often requested to give insight into which characters you have more trouble with than others, but it is not particularly helpful for that. The main issue is that it is heavily skewed by how strong the opponents you play are.
For example, this data suggests my worst matchup is clearly vs Reina, but that's just because most of those games are vs Yagami.
There is a way to account for this being worked on. The central idea is to assign each matchup a rating vs you which adjusts based on the result, much like the regular rating but also based on the rating of each player. With this, it would give a better summary of how well you perform vs each character.
In the meantime, this page is here to present the data as requested.