I don’t disagree with your premise that Leo can be hit or miss as an actor. But your examples are very much confusing me.

You must have watched a different version of Once Upon a Time if your takeaway was Timothy Olyphant > Leo. First of all, he’s in 2 scenes. Second of all, Leo gave a fantastic performance.

And I thought that his performance in Departed is the best in the film, and one of the greatest he’s ever given.

But he’s had had share of duds. And I don’t think, at least from an acting standpoint, that he’s reached the potential that was there in Gilbert Grape. And there’s an argument to be made that a contemporary like Joaquin Phoenix has had a much more interesting career.