I think some of you guys are over-rating the common fan's understanding, accepting and embracing advanced stats. It has certainly come a long way given mentions on national broadcasts, etc. But I think if you polled a typical stadium crowd with the question, "Can you tell me what OPS+ is?" your success rate would in the 5-10% range and I might be overstating. Seriously.
From the thread I've certainly come to a greater appreciation of Valentin, whom I saw many times. If I'd been asked prior to today, I would have referenced his injury proneness. But looking at BRef, I see he averaged more than 100 games a year over 11 years, driven lower primarily by outliers at the begining and end of his career. He put up some very nice numbers. (He's currently the Dodger's assistant hitting coach alongside McGuire, interestingly. His Seton Hall temmates included conincidentally Mo Vaughn and Craig Biggio - Thank you Wikipedia).
Media had a huge influence on fan perception and appreciation back then. While we have an appreciation for the Gammons' of the world in those days, there was a lot of undue criticism of players which had nothing to do with on-field accomplishment or lack of it. And frankly, New England baseball fans ate it up. I think this plays a far larger role than realized today. Player praise was fleeting and getting it meant kissing up to media who were considered by the players to be mostly, "The Enemy."
As for Boggs, I agree most of his exile is on him. A victim of Boston media scorn, yes, but he violated a lot of unwritten rules for which teammates still haven't forgiven him. Every account I have heard is he was in fact not a popular guy in the clubhouse. I also remember him as the un-clutch much as I remember Rice as the DP champ and mediocre defensively (and surly).
I do give Boggs his due though for becoming an above average 3B. He did it through hard work and thousands of GBs. He was not a remarkable defender coming up. He made himself into a plus defender. He is a legit HoF, no argument.
Couldn't care less about the horse or the Devil Ray hat, FWIW.
Underrated seems the wrong word for Boggs. Underappreciated, yes. I still think Bob Stanley is the underrated winner of the period with honorable mention (after today) to Valentin.
Finally, if any of those teams had won or there weren't so many crappy teams during the era, this conversation might be very different.