TP is no better in coverage than Roy. Simply, he had a very good FS playing over the top that allowed him to roam free. He was essentially allowed to freelance all over the place, which led to the number of plays he made.
Also, he REALLY upped his game in the playoffs. The difference between the current reputation of Roy and TP is that Roy unfortunately was beaten in a game that everyone was watching (MNF against the 'Skins), but very, very good throughout the rest of the year. TP was no where as good as Roy during the regular season, but everyone saw some of his great performances in the playoffs. For that reason, he will carry the reputation of being this spectacular player, when in reality there is no doubt in my mind that Roy is the superior talent.