Some clarity on the holding of Com. v. Clarke (i.e., Padilla's retroactive effect)

Clarke held that "we conclude that Padilla is to be applied retroactively on collateral review of guilty pleas obtained after ... April 1, 1997."

My question: What are the implications of this holding?

My understanding is that Massachusetts, by its own terms, is bound to follow Teague. If Massachusetts finds under Teague that Padilla is an old law, how can Massachusetts permissibly place a limit on Padilla, i.e., a fifteen year term?

Thank you.