And Santana has a better adjusted ERA+. And 10th best ERA+ of a 5 year period all-time. 2 Cy Young awards (1 that was stolen), 3 ERA titles, Triple Crown (one of only 12 MLB TCs)
I'm not saying Santana is a Hall of Famer, but to call him 'borderline great' is selling him short. He was elite at his peak.
And to attribute the lack of post-season success isn't purely on Santana. Not even close. Saying Kershaw is a non-Hall of Famer erroneous at best.
Santana's had a very good peak, HoF worthy if he could have maintained that level for 5-10 more years. The same goes for Kershaw, and he needs another 5+ quality years before he's even close to consideration.
The average HoF pitcher has a stat line of: 18 years, 4 ASG, 70 WAR, 251 wins, 2.99 ERA, .589 W/L%, 456 GS, 255 CG, 40 SHO, 3764 IP, 2144 K's, 15532 BF. This includes both starters and closers, different eras, etc. Quality longevity is rewarded more often than great but short peak careers. Post season success (fair or not) gives guys that had it a leg up on guys that weren't on good teams (this is true for all HoF's).
Santana meets a few of the average HoFer benchmarks (mainly K's stats). He actually would fall in the bottom 10 (of 76 HoF pitchers) in years, wins, IP, CG, SHO, Games, and BF (after a cursory glance at the stats).
Sabathia has a better chance to make the HoF, but after he got injured he wasn't near the same pitcher. If he had continued with a gradual decline instead of falling off a cliff he would have been a HoF lock.