Meh? I'm not the biggest Montoyo fan but I also don't think this changes much about the fate of the team.
They aren't losing games because Montoyo is pulling the wrong strings. Sometimes you have a manager who overplays veterans or relies on certain relievers too much. I'm not seeing that from him.
The offense has a terrible approach at the plate this year. There hasn't been an adjustment to their hitting approach. That is far more on Guillermo Martinez.
The bullpen is just garbage. Too many soft throwing guys.
The rotation fell apart when Ryu was bad/got hurt (Jays got incredibly lucky to get two seasons of good health out of him) and then Kikuchi was unsurprisingly bad. Stripling is a good pitcher but it killed the bullpen depth to lose the long-man to offset the unreliable back of the rotation.
This season is more an indictment on Shapiro/Atkins than Montoyo.
I'm also not fussed about firing Charlie though because I don't think he's a manager that is going to bring a team to a championship either. A change was probably necessary at some point in the next 1-2 years for the Jays to take the next step either way. I just don't think firing him now is going to do much to fix a very flawed roster that has to compete in a brutal division.