Its all well and good saying about being on board from the start. Things change. When recruitment goes wrong, whether that means signing shit players, not signing enough players, not signing players that he would like, not signing players suited to how he wants to play, anyone would become frustrated.
Tomasson was on board from the start, he was used to a similar model. But this is Venkys run Rovers. When signings of poor quality were repeatedly foisted upon him, positions he needed were neglected, they slashed the budget mid window etc, its his head on the block and he grew more and more frustrated to the point of leaving.
With Ismael, it may take him longer because unlike the previous 2 he wont be walking into another decent job for example at Championship level anytime soon because this will be his third failed Champipnship job in a row and hes sat on a long contract.