John Terry. He was obviously a very good defender, position and reading the game, very good, and got a decent number of goals from set pieces. However, he lacked pace and couldn't play out from the back, could only really play as a right sided defender, wasn't versatile. Compare that to the likes of Stones, Ake, Laporte and Dias, who can do all the things Terry can do, plus more. He also wasn't the best English defender of his generation, Ferdinand and Campbell were both better, in fact that was England's best defensive partnership at the time. I think King would have been better if it hadn't been for his injuries. Then there's the off field issues...
Jamie Carragher. Similar reasons to Terry, but wasn't as good as him.
David Bentley. Hailed as the next best thing, aside from a decent spell at Blackburn, did nothing of any note at Spurs and never made it at Arsenal.