Right call, you can't just run through the goalie. What was not right was the way the play was restarted.
I've watched it back, the defender kind of bumps into him and his momentum takes him through, not sure what he's supposed to do to be honest. Not sure if Howard would have saved it even if Pato hadn't gone into him.
Ball hadn't crossed the line when Pato went into Howard, hence it's the correct call as it makes Howard unable to attempt a save (even if it may have gone in regardless). Had the ball crossed the line first, it'd been a wrong call. It's quite easy, really.
Like I said though, he was bumped by the defender, it's not as if he wanted to clatter into Howard. Put it this way, had that goal being disallowed against Newcastle, I'd have been furious.