I shook my head after one scene, and then after another, asking "what the heck just happened?"
I admit that I have never seen the two earlier movies in the series. But it doesn't seem that this was the problem. This is a standard action-adventure flick that presumably was meant to be viewed on its own. Heck, I saw only the most recent of the "Fast and Furious" movies, and had no trouble following it at all.
Maybe, as to Expendables III, somebody was too busy getting all the big name stars to sign up to concern him/herself with matters such as plot or screenwriting,
Just a thought.
Did this mess make money?