What he did from 2014 until the end of his career probably didn't help his HOF case even a tiny bit.
He accrued almost no WAR as a primary 1B, he didn't get over any important milestones during that time, he had 4 of the worst season batting averages of his career.
I guess the voters are just saying that his career through age 30 was good enough to make it.
And I do think he really looked like a hall of famer most of that time. Dude was a pure hitter. He hit .319/.401 in that time period. The only other .300/.400 hitters qualified from 2004 to 2014 are Helton, Bonds, Manny, Pujols, Votto, Miggy. Kind of nuts for a viable catcher (during this time) to be on that list with pure 1B/DH sluggers.