All hockey stats need to be taken with a grain of salt, but generally, the consensus of statistics will paint a pretty good picture.
AMac wasn't horrible (he could look pitiful at times), he was good at goal suppression, and generally was a generic 3rd pair defenseman.
Gudas was a top 3rd pair defenseman, but advanced metrics overrate him b/c they don't really account for usage, that is, if you shelter someone, they'll put up good metrics - look at Sanheim with Gudas on the 3rd pair v Sanheim's numbers with Provorov on the 1st pair.
Voracek was a very good player until three years ago, when his defense went from average to above average to among the worst in the NHL. That's why he doesn't do well on advanced metrics, he scores but doesn't contribute much else.
JVR was a solid player with Bozak in Toronto, I think he can find similar chemistry with Hayes.
TK really fell off defensively last season, especially under Gordon, but at 22 and playing for a HC who will ride him hard if he makes similar mistakes this year I expect a rebound. He's got the motor to be solid defensively, and the fireplug body to forecheck, but he goes brain dead at times.
Myers got his feet wet, but I can't imagine him putting up similar bad metrics this year with Ghost as his partner, once they figure out how to work together, they should push for top 4 PT.
The Flyers have a lot of players who can elevate their game this season, it's up to AV to get them there.