We could do with some more depth. I understand it varies how many games a player can be expected to play in a season, but I wonder if there is a general 'red zone' when we should start to worry.
Out of nowhere, I decided to put the limit at 40 games and then check. The following players have taken part of 40 games or more for us this season, in all competitions:
Firmino 47+5= 52
Salah 47+3= 50
Wijnaldum 38+10= 48
Milner 25+21= 46
Mane 41+1= 42
AOC 21+21= 42 (excluding 4+0 for Arsenal)
Lovren 36+5= 41
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Henderson 35+4 = 39
Can 34+3 = 37
Building on that, I suspect that players who make more sprints will be more vulnerable. In our case, following that line of thought, we should be mostly concerned with the front three and AOC. But if we look at AOC, we can see that he has as many starts as he has sub appearances under Klopp. This must be our way of making sure we don't overplay him. He got injured anyway, but not because of us overplaying him. Looking at the list above, I'd say we have a good distribution of games between our CMs.
But once more we come back to our front three. They have all not just played in more than 40 games. They are the only ones who have started in 40+ games. Salah in particular, having played the most minutes of all our players in the PL, surely must be in that 'red zone'. I suspect this summer's World Cup isn't ideal if we think of Salah's fitness preparations for next season.