We have had similar issues with group activities, even though DS is an extrovert. Honestly, repetition has become a major issue too. We have recently cut music due to repetition, even though he loves music... He doesn't love music class. We have had luck with parenttoddler gymnastics, where he has the illusion of being around age peers, who are very closely supervised, but the teacher can differentiate for him and fully demonstrate what is to be done.
We have had two things work well...
One is a family with an age peer and older sibling who are very verbal. DS follows the older sibling and the age peer follows DS. They have very attentive parents, so I suspect that is pretty key.
The other is his Strider Balance Bike. He rides well now and at the park can keep up with the older kids. They just ride around and don't talk much but he loves it. In the Spring, he will be getting a bike with pedals, no training wheels, and I suspect this will help even more. The other kids just assume he is much older than he is.
I have given up trying to push him into playing traditionally with age peers. YMMV.
