He wasn't in the one-sees he just wrote the song.
I saw them last week in Pittsburgh and got up on the stage to play "Hey Julie" with them for the second time. I think he was using the Jazz bass to play the older songs, and his Gretsch for the newer stuff. I've been to their show 5 times now, and the most recent was the only time Ive ever seen the Jazz. Awesome show any way you look at it.

That's me third from the right. Tall guy next to two shorter ladies. I walked on stage and Adam Schlesinger asked me "How I have been doing" and that is was good to see me.
Super nice guys.
E.