Bouwmeester is a slightly better iteration of Quincey with a far higher cap hit. His primary assets are his skating and his durability. He is average on offense and not much above average on defense. He is certainly not worth the assets and the loss of cap space that his acquisition would require.
Bouwmeester locks big minutes, can give you a solid offensive punch and is a reliable shutdown guy, his cap hit may be a bit high but if the Blues are re-signing Pietrangelo, there aren't any good UFA defenseman available in the future.