Yes McMeeken can't tackle, he would get shown up at a higher level. Unfortunately you can say the same about McShane, especially with his goal line defense.
I don't think Wane is an idiot, he can spot the difference between a good player and a poor one and he isn't going to pick a poor Wigan player over a good Saints player. The only problem is he is taking over from the best coach in the world for the last 30 years. If Wayne Bennett can't make this set of players look good then I don't think anyone can.