Bouwmeester is only two years older than Keith and with his skating ability would make the perfect partner for him. Alternatively, Chicago splits them and pairs them with Hjalmarsson and Oduya/Rosival. Stajan provides them with a third competent center, someone who can either take the 2C position or play 3C and allow Bolland to play 2C - thereby allowing Kane and Sharp to stay on the wing. Babchuk provides an upgrade in skill on defense without losing size.
Seabrook for Bouwmeester is close to a wash in on-ice value, Seabrook probably has more trade value due to age and contract. But all Chicago has to give up for Stajan + Babchuk is Montador + Frololololik.
The only way Chicago says no is if they're intent on not dealing Seabrook; it's clearly favorable to them and not in a marginal fashion.
Why are we trading Glencross for Purcell? Purcell can't pk and plays a large majority of his 5v5 time with Stamkos and plays with Stamkos and St.Louis on the pp. He will not produce 60+ points with out them he would be the same player with out the defensive edge to his game.