Your players are of high enough quality to win the league, end of story.
No Pep would not win the league this year because they're mentally a shambles, and already too far behind. But he might win it next year or the year after. I'm pretty sure Mourinho won't, even with a lot more investment. He's already peaked last year with this team, that's how he rolls, time and again through his career.
Pep signed Mahrez, a proven EPL performer, he comes in and does a job. Mourinho signs Sanchez, a proven EPL performer, he's on the bench and a shadow of his former self. Perfect example of the gulf in class between Mourinho and Pep right now.
That is only your opinion. There are lots of EPL pundits that disagree and former Utd greats. Even Keown has said so.I know which of these I would believe before you.
https://www.skysports.com/football/news/15115/1154...
This is only one that I have read of in the past few weeks.