Well you need to learn how to engage them.
The drill I use to teach it is as follow:
-
Set up on the bench and hold the bar as if you were going to do your bench press.
-
Have a partner stand behind you (where a spotter would be) have have him try to pull the bar toward him, you resist him to present the bar from moving over your face. He pulls just enough so that you have something to fight against, since you are keeping the arms straight, the lats will do the work, which is the feeling you want when setting up.
-
Slowly lower the bar as if you were going to bench press it. During that time your partner goes down with you (ok that’s weird) still trying to pull the bar toward him, that will teach you how to keep the lats tight during the eccentric.
-
Then you slowly push the bar up, still with your partner doing the same thing.
This drill will teach you the feeling of engaged lats in the bench press. With enough practice you will be able to copy that feeling when bench pressing and then you are golden.