Who got better under whom? Who got worse?
Every player's output the season before a coach, under that coach, and after. Ranked. Gasperini has the highest share of risers: 13 of 30 players.
We tested the big question
Does the coach matter? In this data, not detectably.
We compared 57 coaches with at least 3 club-seasons, using players in their first season under a coach. The differences between them were about what chance produces (p = 0.41, test written down before the first run). A coach's effect at one club also did not predict the effect at another (r = 0.12, 57 coaches). The swings below are real, and that is why they make good arguments. They are just not proof. This covers attacking output only, with nothing on defending or roles.
Season before, under the coach, season after. Non-penalty xG + xA per 90.
1Aleksey Miranchuk
under Gasperini, Atalanta
2Mateo Retegui
under Gasperini, Atalanta
3Luis Muriel
under Gasperini, Atalanta
4Harry Kane
under Tuchel, Bayern Munich
5Ademola Lookman
under Gasperini, Atalanta
6Gianluca Scamacca
under Gasperini, Atalanta
7Mauro Icardi
under Tuchel, Paris Saint Germain
8Marco Brescianini
under Gasperini, Atalanta
9Joselu
under Ancelotti, Real Madrid
10Mikel Merino
under Arteta, Arsenal
11Layvin Kurzawa
under Tuchel, Paris Saint Germain
12Jeremie Frimpong
under Alonso, Bayer Leverkusen
13Samuele Ricci
under Allegri, AC Milan
14Duván Zapata
under Gasperini, Atalanta
15Noni Madueke
under Maresca, Chelsea
16Emil Holm
under Gasperini, Atalanta
17Fabián
under Ancelotti, Napoli
18Leroy Sané
under Tuchel, Bayern Munich
One player is one story: a swing can be injury, a new role, age or luck, and a good team feeds everyone. The median year-to-year swing of a big-5 player is 0.05. Nothing here proves a coach caused a change. "After" is the next full season away from the coach and is often at another club. Data through 2025/26.