Jarvis had his best seasons under Gase. He was a good player then, and a good player now. Parker's "ascension" came with the same staff Kenyan Drake had the opportunity to play for, and didn't do anything with. Tannehill, sure. Drake is a role player, a role player with history.
Ah, yeah, let's ignore that he had 8 TDs rushing and receiving in those nine games, and more than 100 yards receiving.
Henry had 3 games under 70 yards rushing, one being 69, in 15 games. He was a consistent factor. Drake had 11 in 14. He was not a consistent factor.
Kenyan Drake is a complementary player, simple as that. He was at Alabama, he was with the Dolphins, he is that here.