Given how much money Marvel Studios clearly spend on assembling some of the most impressive casts in the history of cinema (to the point where they can call on Matt Damon for a tiny gag-cameo), you'd think that they'd be careful with how they use the talents available to them.
Now, obviously, balancing casts with lots of very good actors will inevitably come with some compromise in terms of character development and screen-time for balance, but the studio would surely focus on making sure their most gifted actors get something substantial enough to justify their inclusion. Otherwise, all they've done is give a great actor an unsuitable, inferior role that could have gone to someone else, freeing up the original star for a better role further down the line.
Sadly, hindsight tells us that that clearly wasn't always the case with the MCU, as there are some incredibly gifted actors who have - for one reason or another - looked completely wasted in the roles they were given. Whether that's because of a problem with the material or just miscasting, it's happened quite a few times.
Some actors have been used to perfection, of course, but others - whose talents deserved a lot better - really weren't...