Note how he says you could blame the writer and the director for the more daft stuff but he couldn't bring the less bizarre scenes to life as an actor.
I doubt if any actor could pull off the monkey business.
He doesn't do too badly in the less silly scenes but in any film injected with such jarring material a so-so performance is going to look and feel worse.
He's just a bit bland, not really awful (possibly because he had assistance from other actors and an experienced director) but he says his lines he looks the part but he's in a film with sudden bad computer game action.
He puts the blame for that on Spielberg, he should point the finger at the guy who insisted on putting those elements in which was neither the writer or the director or even himself.