Yes, he is, which is why Giles got signed by a prem team, and why we tried to keep him before singing two left backs. He went to the wrong prem team mind, which I said at the time. He needs to play for an attacking side, as you're right about him not being all that strong defensively, he was never going to suit playing for Luton who have the ball maybe 25% of the game.
Defending isn't the only role for a defender, football doesn't work like that anymore, especially not for wing backs. If you're little threat going forward oppo teams can take more risks on that side, and throw more men forward as they no you have no threat to counter etc. Being a good attacker is a great form of defence, as it makes teams wary to attack or push people up on that side. Being a better attacking left/ right back is also important if the other side can't attack (like smith couldn't last year), and it's even more important again if you're going to have the ball more than you don't have it.
1 assist in 12 games I think it is for Engel, but I don't recall him putting in many other good balls. Giles had what 12 in 45, 2nd best in the Champo? That's miles better. Most of Giles were fairly early on in the season too, and once teams realised how much of a threat he was they overloaded that side to counter it. This freed up space elsewhere, which we partially capitalised on. Never mind how many other good balls Giles put in, when we actually got him the ball.