I didn't realize he was on the show, I stopped watching Nurse Jackie around the time that kid od'd.

"My goat knows the bowling score"
Wait a minute who am I here?

I agree. He was great on Nurse Jackie. Excellent portrayal of a good guy with flaws. Clearly, the kind of person Jackie could relate to.
You mentioned Monk and Wings. Well, I have only randomly seen Monk so I don't have much to say about that. On the other hand, I watched Wings just about every week when it originally aired. His character was an immigrant on that show and he played it so convincingly that I thought he was an immigrant himself. I remember being very surprised when I found out he is actually as American as apple pie, born and raised in the Midwest. So, I'd say he did an excellent job with his character on Wings. He had me fooled.