They did, but they are 29 and 28 years old, respectively. In the prime of their careers. When Paul Konerko was that age, he was enjoying some of his finest seasons. He led us to a World Series title at age 29. Now, Paul is 36 and more prone to injury. He's not the only older player in the Sox lineup who struggled down the stretch either.
It is worth noting Alex Rios led the Sox in games played with 157, and he did not fade at all. He played some of his best baseball down the stretch while teammates were crumbling around him. Rios is 31, a little older than Cabrera and Fielder, but still young enough to handle a huge workload. Two of the five games Rios did not appear in this season were the final two meaningless contests in Cleveland.
As for Verlander, check his August and September numbers
for his first full year in Detroit's rotation. That was 2006. I think you'll see he had some struggles as a young pitcher, much like a couple young pitchers in the Sox rotation this year. It takes a little time to build up the kind of arm strength where a pitcher can handle a 200-plus innings haul. He's at a much different place in his career than say, Chris Sale.
As a matter of fact, Detroit's best players are all in their primes. The Sox best players are mostly on the back end of their careers, or in the case of a few pitchers, just getting started. That makes a difference.