Pinot is almost always prominent until he decides some calamity or another should befall him. Porte is usually just kind of there until he isn't, and when he does crash out it's often before a reasonable guide to his form can be seen.
Many races have been better for Pinot being in them. I can't possibly comprehend that anybody other than a myopic Aussie has ever looked at a GC battle at any Grand Tour and thought "you know what, that race would have been better with Richie Porte in it". He just retreats into his shell in three week races when he's the leader, much like Valverde. He's a much more active, much more proactive, much more dynamic racer in short stage races, but in the GTs he completely forgets that side of him exists. Either that or he's so paralysed by fear of losing time that he's too scared to try to gain it.
He would need a DS committee of Jacky Durand, Aleksandr Vinokourov and the ghost of Frank Vandenbroucke to wring anything interesting from him in a Grand Tour. He's been touted as a GT rider for a decade now, yet his record is no better than Ronan Pensec or Walter Riccomi's. He's a great one week rider, and he's now 35. At what point is he going to stop banging his head against the three week wall?