Most actors are pretty bad, depending on how you look at it.
I think most "actors" just read lines.
The best actors become the character.
One of the problems though, is that a lot of the writing on TV shows and movies is so poor it doesn't really give an actor the opportunity to even become a character.
This isn't really to criticize The Wire. The Wire is one of the all-time great TV shows because of the way the stories are intertwined and told. But it's not exactly the best "acted" show there has been.