Another option for you.

If you used to excel at one aspect of the game (tower defense), but due to changes which you have no control over... are having difficulty there...
Change your tactics.

Maybe rush to a graveyard and cap that early.
Or play a couple games where you're on defense, stay out of the thick of combat, but absolutely litter the bridge with totems and spam chain heal with your team each targeting a different primary defender who is also on the bridge.

There are different things required to winning an AV.
Towers are one, but that's not the only thing needed.
Pick something else -- maybe control of a choke point, and contribute there instead.