They seem to get stuck in their own heads a lot and have a hard time looking at cards in a vacuum of "duh thats pretty good"
I feel like there's a synergy angle that's usually where these guys miss out. Collected Company is fine on its own but better than they expected; Reflector Mage is good when they expected it to be okay; the result of both misevaluations here multiply out to be much more than the issues in a vacuum. This is the most common failure mode for R&D in recent years -- underestimating two different things a little bit, causing them to miss a massive synergy between them.
Jace, though, that's just straight-up failing to evaluate a card correctly.
While I've been out of the loop all along and this might come off as "old man yells at cloud", what's the deal with so many people turning to speculation with MtG?
This is actually the same thing that happened in the very early days, until the massive reprints happened and print runs stabilized.. Then there were something like ten years where recently printed cards didn't meaningfully appreciate post-Standard because the player base was reasonably steady and everything was in plentiful supply -- plus formats using older cards were actually pretty unpopular overall so you didn't see a lot of cards spiking because they were in good, popular decks.
Then the game's popularity massively spiked with Zendikar, which resulted in the player base getting
way bigger (and current print runs to match); that same period of increasing popularity also covered the rise of EDH and Modern, both of which are far more popular than older-card formats were in the past. The end result is that suddenly cards from a huge window of time (Urza's Saga to Alara, pretty much) had the potential to massively spike when they previously would not (since now their small supply was insufficient for the number of players.) Once that happened a few times, people got the idea that card values could majorly fluctuate and got more and more into playing the market, both to protect themselves from spikes and to potentially profit on them.