I think GSP outstrikes him whenever the fight is on the feet. Once he establishes his takedowns, his opponents really seem to be really hesitant to pull the trigger. He did it to Penn in their second fight and Alves who are both arguably better pure strikers that GSP.
Ya you're right, but Alves doesn't have the best TTD. BJ has phenomenal TDD, but it is based more on his pure flexibility and balance on one foot, which wears over time. Silva's TDD is based more on the sprawl and he also hip escapes beautifully when you do get him down.
When you get BJ down he is able to use rubber guard well, but rarely does he hip escape or get a reversal unless your name is Matt Hughes.
I like Erick's chances in the fight and think his striking is more effective than GSP's.
Shields has absolutely horrible hands and very rudimentary striking imo and he was able to hang with GSP. A guy like Silva with that power and speed with great take down defense, BJJ and athleticism would be a tough fight for anyone including GSP.
The only downside to him is his size imo. By no means is he small, but bigger guy's like GSP, Fitch and Alves make him look small for the division.
Luckily, skill is far more important than size in the fight game.