Quinn seemingly does a better job of putting his players in a position to succeed than Moore does. Moore also likes to get too cute at times. They also sometimes go away from what's working...with moving away from Zeke against the Bucs being the latest example.
Dak has always had limitations, but the biggest issue to me more recently, is that he's been playing scared since the 2nd half of last season, and It's affected everything. And now injuries are piling up.
Supporting cast can also of course matter a great deal.
Game one against the Bucs last year (same QB and OC): Cooper, Lamb, Gallup, Wilson, Schultz, Jarwin. Cooper caught 13 passes for 139 yards and 2 TD's ... and as the #2 Lamb had 7 catches for 104 yards & 1 TD.
Game one against the Bucs this year (same QB and OC): Lamb, Brown, Houston, Schultz, Turpin, Fehoko. Noah Brown led the team with 5 catches for 68 yards, whereas he was inactive or didn't breach the stat sheet the year before!
The above is a massive difference of skill position production and talent...not to mention the difference between the two starting O-Lines!