Garrard wouldn't have been able to make it on the field. You notice no one picked him up? He wasn't healthy enough to play this year.
Gabbert isn't as bad as everyone is saying. He has no time to throw the bad and the WRs cannot get any separation. If he throws the bad when the pressure gets there, it will either be intentional grounding or a lot of INTs.
Gabbert is also only playing his 3rd season of college/pro ball. He had no off season and terrible coaching under Del Rio and staff. You have to wait until next year and see what he does with the off season and good coaching.