No one expected Uehara to be as brilliant as he was in 2013, but he had pitched like a stud before that and the main knock when we signed him was the question of whether he could stay healthy.
Salty had his best year, but only by 1.1 bWAR up from 2012, when he hit 25 home runs with a .742 OPS.
I would characterize Nava and Carp as the only real stunners who were never able to come close to their 2013 performances either before or after.
A lot of fans pooh-poohed the signings of Victorino, Napoli, Drew, Gomes, etc. and then, after the season, tried to pretend they were right all along by rewriting the seasons those guys had as "career years"...when, in reality, they were solid players with established track records who performed on the higher end of what might reasonably have been expected from them.
The idea that the 2013 championship only came about through dumb, blind luck, through an unforseeable confluence of career years and lucky breaks, is one that irritates me to no end. Not only is it factually false (notice how quickly we went from "everyone had career years" to maybe three guys did - our third string closer, catcher, and platoon left fielder), but it ignores how much adversity that club actually had to navigate, from the injuries to Hanrahan, Bailey, and Buchholz, to Middlebrooks completely flopping relative to expectations. It was not a team that ended up being built for long-term success (something that could fairly be said of the 2004 Red Sox also, and may soon be said about the 2018 version once its major pieces start dispersing), but that doesn't mean what happened that year isn't valid or should be discounted.