The record says Garrett was a better coach .559 winning % compared to .520 winning %. and Yes Garrett left the boys in pretty good shape, much better than he inherited. Now I know you hate him and will never admit that but doesn't make it any less true. Ask any Texan fan, the Texans are a complete dumpster fire thanks to BOB, gave up way to much for a LT, traded away the best WR in the league for nothing, the QB is refusing to play (not to mention all the off field issues), the cap is a complete mess and they have no draft capital to speak of.
Garrett left one of the best O's in the game - QB, RB, WR and OL all better than average - when healthy. The D has always been the struggle and he deserves fault for that for sure, but overall, no one in their right mind would think BOB was a better anything than Garrett.