Here's my view on it.
From a league context/popularity perspective, Olerud is far behind all three of these guys. This isn't entirely his fault, he's an advanced stats darling who mostly played in an era where the things he did best weren't yet fully appreciated as they are now.
Olerud's accolades are 2x AS, 3x GG, a batting title, and the fact that he was a part of 2 WS champion teams, but not the most popular player in them. Not a single Silver Slugger is a big detriment to his case, although he arguably definitely should have some. I think his two 8 WAR years being so far from one another also hurt him in popularity, if he repeated those in 93-94 or 98-99 he might have some more notoriety. Instead he was more "boring" good around those seasons, instead of a force to be reckoned with.
All in all, Olerud only had 3 seasons of 5+ WAR production. Compare that to:
Keith Hernandez - seven 5+ WAR seasons. 1x MVP, 11x GG, 5x AS, 2x SS
Don Mattingly - four (consecutive) 5+ WAR seasons, 1x MVP, 9x GG, 6x AS, 3x SS, bonus: played for the Yankees
Delgado - three 5+ WAR seasons, 2x AS, 3x SS (in peak steroid era), bonus: 473 career HR which is about as much as Mattingly and Olerud combined. Allegedly clean(?) player in steroid era who still had monster numbers
To me, from this list Keith Hernandez is the only guy who should most likely be in the Hall. Mattingly had the peak and popularity but not the longevity. Olerud is missing the popularity and the peak. Delgado probably just broke out too late to have a shot, and the missing 27 HR to gain him "automatic" induction is probably what costs him.