Stotts isn't a top-tier coach, nor is he garbage. He's one of the broad category of coaches that doesn't matter if the talent isn't sufficient. That's the vast majority of coaches.
The Blazers are a generally mediocre team. That's why they were the #8 seed. They're getting killed by the #1 seed, as expected. I'll believe that Stotts is the problem when he has a cast talented enough to hold back. Right now, the only star on the team is Lillard. McCollum is a good player who isn't an ideal fit and Nurkic is a good player who also isn't an ideal fit. Gary Trent Jr. may be a great piece in the future, but for now, the rest of the supporting cast is small potatoes.
The last time the Blazers had a really talented team was in 2014-15, when they had Lillard, Aldridge, Batum and pre-injury Matthews. And Stotts definitely didn't seem to be holding that team back. They wouldn't have gotten past the Warriors that year, but they had a shot to be the second or third best team in the NBA.
I'd be fine with replacing Stotts if a better coach is available. The idea that Stotts needs to replaced at all costs is silly to me.