I think its easy to miss some concerns from the outside, Leicester fans are rightfully addressing some glaring concerns, some of which have been evident since the turn of the year.
His use of subs is often appalling, waiting too long to make any to begin with and when he does, as with yesterday, they are the wrong ones, Praet and Perez were playing well and 2 of our more effective players, now there may be reasons both had to come off but no explanation has been given to my knowledge and despite having another sub left Iheanacho was left on the bench in a game we were losing 1-0, fans are obviously furious with that.
Watford away his use of them cost us the game, he made 3 single subs, meaning we couldn't use the extra 2, the second and third were made within a few minutes of each other, had he just made a double change when Chilwell scored we could of brought on an extra defender to help at set pieces, which Watford had been troubling us with all game but we couldn't and they scored from one.
Then there his insistence of a 433/4231 system, against Brighton he played 2 pure DMs in Ndidi and Mendy, which Puel used to do and it never worked, shoved Maddison on the left wing, where he is totally ineffective and had Iheanacho playing behind Vardy, it never worked, never looked like working and players were lost. Instead of just changing the system, which we have players suited to a back 3 to do so. Also the players simply do not look as fit as other teams do.
And whats really annoying is the easy ride he gets from media, there are questions that any other manager would get asked that fans want answers to that he never has to face, this lead to frustrations in the fan base boiling over and some vented them in the thread linked to above, no one is seriously questioning his future, but this much is clear, having been in the top 4 all season, to finish out of that now IS a failure.