I think this is not fair to say at all.
The squad isn't really that great, all other top 4 teams have more world class players and all of them have better strikers and better back up strikers on their benches. So getting top 4 is an improvement from last season, that's an anchievement all things considered, ffs we got top 4 playing without a striker that's worthy of Champions League football.
Sarri came and changed our system, we looked weak in defense for most part of the season and we look clueless in attack most of the time, even so Sarri got the result and deserves some credit for it because our goal wasn't to compete for the title but to get Champions League football.
Remember that last season it was a gap of 30 points, Man city had 100 points and we had 70, now they have 95 and we have 71 with 1 game to go, Sarri might not be the long term solution but this squad can't do much better than this so we shouldn't sack Sarri when he actually did get us where everyone wanted to end up!