Totally agree with that, GM.
I think Song's biggest problem was that he was slow. And not just slow... cumbersome. Couldn't release the ball quickly enough, couldn't turn fast enough when we were dispossessed. That's why he accumulated so many dumb cards. Someone like Coquelin is on his heels and ready to move with the opponent the second the game turns. Song was planted in the ground like a tree and too often had to stick out a leg and hook the other guy. The games where he sat back and defended he got less exposed to these situations, but we got a lot more more out of him when he joined in with the attack.
Technically he transformed into an excellent player in his latter years. Passing range was good, vision was pretty excellent. He just took way too long to execute, and to react, and at top level you get found out when you play like that. You look at Ivan Rakitic at Barca right now and think to yourself that he feels badly out of place. And Rakitic is twice the midfielder Alex Song is. But he still gets found out because he's too slow and dwells too much in a team where one-touch football and quick transitions are at the heart of everything.