Well, Bosh is a bit like KG where he's a good weak side defender and great on the perimeter because he's light-footed (

) and agile. In his three years on the HEat I think he's been very impressive in defending picks. I'm too lazy to look up stats, but I would be the heat are overall very good at it.
I thought the HEat had the edge in this series because they could put Chalmers, Cole, and Lebron on TP. However, 1-1 only Lebron has been able to contain TP. Cole has been a disappointment.
Take a look at TP's two favorite plays. When he's doing his REggie impersonation and coming off screens, he just ditches Chalmers and Cole (and the rest of the league). Lebron stays up with him and Bosh will often jump out to harass TP and knock him off position. BOsh will recover quickly as well.
When TP has the ball and is getting screened, Bosh is very effective in harassing him. This is not new though, Bosh has been impressive with his perimeter defense ever since he joined the Heat.