Twellman was very, very good and should have had a much longer career. Luckily, he's pretty and is also good in the booth, so he'll have a long career in broadcasting if he so chooses.
The big thing Twellman seems to have going for him is his USMNT and MLS inside knowledge. He often seems to know of things happening well before they happen. Not sure if it's because he still has contacts from his playing days or not. As he gets older, he may have a challenge keeping his channels to inside knowledge available.