actually, if you look at the top 10-15 gb% you see more low babips than high.
and sanchez' 17.8hr/fb% as an SP is just as likely to be due regression.
and the most encouraging part of his stint as SP was the drastic improvement in bb% by the end of it.
Those with under .300 BABIP and >50% GB rate: Dallas Keuchel, Felix Hernandez, Jake Arrieta, Garrett Richards, Kyle Gibson, Chris Heston, Sonny Gray, Mike Leake, Kyle Hendricks, Francisco Liriano, Jimmy Nelson, Clayton Kershaw.
Out of 22 pitchers, that's 12. Obviously that's a majority, but we can excuse Heston and Hendricks considering they are .04> of .300, a rather insignificant margin. So yes, close to 50 percent of the extreme groundball starters have a below average BABIP. 9 of those 10 pitchers also have an above average swinging strike rate (>9.3%). The only one that did not was Mike Leake.
Mike Leake is noted as a character of consistency, but there are several flaws with his batted profile type. The plus is his obvious ability to generate groundballs, another is his ability to limit walks (although this past year was the highest since his rookie season), but his negatives are obviously his inability to strikeout players, as well as his proneness to liners (as well as home runs).
The only saving grace, to this point, is that Leake doesn’t allow many fly balls, and his relatively strong batted-ball mix keyed by his high grounder rate conceivably could carry the day despite the relatively loud nature of his FLY/LD contact allowed. Leake allowed actual grounder production of .172 AVG-.181 SLG last season, good for a minuscule Unadjusted Contact Score of 43. Once you take authority into account, however, that figure jumps to 112. Yes, he allows harder-than-average grounder authority as well. On all BIP types, there is a huge gap between Leake’s 83 and 111 Unadjusted and Adjusted Contact Scores, respectively. That is by far the largest negative differential among 2015 MLB ERA qualifiers; in other words, he was the luckiest starter in baseball last season.
http://www.fangraphs.com/blogs/the-upcoming-mike-leake-mistake/
Essentially what this boils down to is the limitations of groundball/contact oriented pitchers. Batters typically hit for a higher average on groundballs than flyballs, that's a fact. If a groundball pitcher is not suppressing runners by limiting his walks and allowing for lower contact rates with swinging strikes, then ultimately there isn't much potential ceiling. Leake has had the advantage of working with a great Reds defence over his career which has certainly helped raise his floor. Sanchez could potentially have that as well with the Jays. What I am arguing however is that he has not taken a step forward in actualizing any sort of effective talent as a starter. He hasn't shown pitchability, refinement, command, control, whatever. At this point it's velocity and flashes of dominance. His improvement over four or so starts at the MLB level does not provide any sort of proof to the matter. If he is to be a starter going forward, then he should be working on that in Buffalo.