The Chiefs picked up Marcus Allen when Allen was 32 and he was effective for them for 4 more years.
True. But their careers don't really compare in that way.
Tomlinson has had
3410 touches (carries and receptions) thus far in his 9 year career. In Allen's first 9 years in the NFL he had only
2363 touches; Tomlinson had almost 1.5 times as many (a third more) touches in the first nine years than Allen. Allen had
3637 touches in his 16 year career.
In Allen's final two years with the Raiders, before going to Kansas City, he had only 173 touches, total. So basically he had a two year period to recuperate, while staying in playing shape, before finishing his career in KC. Tomlinson has averaged 379 touches per year.
Tomlinson has had nearly as many touches (collisions) in his nine year career as Allen had in 16 years. He was the San Diego offense for a few years...
In the right situation, Tomlinson might be productive. But any team expecting for him to be their workhorse, as he was in San Diego, is going to be disappointed at the outcome.
By the way, Jerome Bettis
3679 touches in 13 year career.