Santini was sent down because he was waiver exempt. Shero made that crystal clear. And Santini wasn't better than Lovejoy last year, or at least by not enough of a margin to send Lovejoy down to Bingo. Basically, the Devils would not have been any better or worse last season with or without Lovejoy. In the same way, I imagine that the Caps would have still won the Cup if Lovejoy was their 6th/7th defenseman.
I think keeping a vet on your roster (for fear of losing him) and shipping the waiver exempt guy down certainly doesn't comment on who was 'better'. Santini played first pairing minutes with Greene for his entire time up - he didn't exactly thrive, but as a 22-yr old, I think that's to be expected.
Our pipedream was Scott Stevens lite, but the reality is that he has the skating, physicality and head to be a top-4 shutdown guy and I think his passing/vision is, while nothing to write home about and weak compared to Butcher/Severson certainly underrated.
As a fan of defensive-defensemen who can play in any situation and help goalies keep the puck out of the net - I like him better than Severson and Butcher and hope he reaches his potential of being that solid guy that anchors a defense.
Oh, I'll warn that this post will likely spark the schismatic Severson-Santini Corsi debate.