I'm afraid your situation can't be easily explained. Think it's a bit of randomness and bad luck at a bad time in the season. I noticed some of the skaters that were injured had low-ish endurance, but nothing out of the ordinary for your league level - and you definitely aren't overplaying them. Your goalies also seem to have a nice rotation. If you or your opponent were playing Hard or Dirty it might explain things a little more, but I have no insight into that.
As far as what leads to players getting injured more frequently in the game, there are numerous factors.
- Injury proneness of the specific player
- Player fatigure... players being exhausted are more at risk of suffering an injury. There's a few things that impact player fatigue... too much ice time, low endurance, training intensity.
- You or your opponent playing Hard or Dirty