Having researched this area extensively as part of my PhD, the reason for our injuries can be attributed to a number of things, including:
- Players exposed to fixture congestion (i.e., 3 matches in 7 days)
- Lack of sufficient recovery between these matches
- Suboptimal baseline levels of fitness
- Players participating in matches when not fully recovered (increasing susceptibility to soft tissue injuries)
- Players returning from a previous injury and exposed to high match and training loads too early
- Exposing players to a style that induces large loads on players and not taking in to account external factors
The last four are obviously all intrinsically linked, and can all be controlled by one man - the manager. So Pellegrini is definitely to blame.
Like Arsenal, the reason they are susceptible to so many injuries is due to Wenger's methods. The same with Klopp, latterly at Dortmund and now at Liverpool.
Pep's players also have high rates of injuries so don't expect it to change next season.