"Methods: Fifty-one football teams, comprising 2,299 players, were followed prospectively
during the years 2001 to 2009. Team medical staffs recorded individual player exposure and
time-loss injuries. The first-team squads of 24 clubs selected by UEFA as belonging to the
best European teams, 15 teams of the Swedish First League and another 15 European teams
playing their home matches on artificial turf pitches were included. A muscle injury was
defined as “a traumatic distraction or overuse injury to the muscle leading to a player being
unable to fully participate in training or match play”.
Results: In total, 2,908 muscle injuries were registered. On average, a player sustained 0.6
muscle injuries per season. A squad of 25 players can thus expect about 15 muscle injuries
per season. Muscle injuries constituted 31% of all injuries and caused 27% of the total injury
absence. Ninety-two per cent of all muscle injuries affected the four major muscle groups of
the lower limbs: hamstrings (37%), adductors (23%), quadriceps (19%) and calf muscles
(13%)"
Found this outline of a study of muscle injuries in football on Google. Seems like we might get a similar number to what you'd expect, but have the misfortune of them seeming to affect players who play in the same position at the same time leaving us short. Also although our squad is 25(ish?) we'd consider ourselves down to bare bones if Small forest, Burke or Crowe were selected, other richer Championship teams have huge squads with internationals and players with PL experience on the bench so may miss players less (or seem to to those looking from the outside)