When a BABIP differs from .312 to .234, a good part of that might be tighter defense, lower velocity on balls in play, more skyballs, etc.
But bear in mind that the team BABIP's last year ranged only from .280 to .322. The year befor the lowest team BABIP was .277. etc. When hits on balls in play (for any team or pitcher; doesn't apply for individual hitters) dips under the 27% mark, then long-term we can confidently predict them to bounce back.
The ocean covers 70% of the earth, and the 8 fielders out there are going to cover about 30% of that two-three acres, however we slice it. Defenses and batters can adjust and adjust back; there's always going to be about 70% out there that fielders can get to. Less than about 27% of the balls are falling in? Something's skewy, and should revert.
I dunno, maybe 50% of the M's lousy batting average vs Texas was their own fault and 50% was the luck of the draw.
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If Texas had been swinging the bats so much better than the M's, we're left with explaining why they fanned so much more, and hit fewer home runs. Put the 1975 Reds against the 1982 Mariners, for 500 at-bats, and the Reds are not going to fan 50% more and hit fewer homers. :- )
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Sometimes the D-stats vary from one source to another. Baseball Prospectus gives the M's and Rangers as having exactly the same out conversion rate, 71.5% to 71.6%. Park-adjusted has us a little bit ahead.
To my eye, the Mariners SHOULD HAVE had a dubious defense this year, but that infield has been very crisp with Cano's recovery and Martin has been superb in center. The corner OF's have been kludgy but hasn't cost us that much on visible plays. Hence the M's consistent top-10 ranking on BP.
John Dewan does have the Rangers with a terrific defense, though, +23 runs saved to his count with the Mariners -13 (mostly at pitcher and catcher!) You could well be right that the Rangers' defense is a big overlooked advantage in our games with them.
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I know what you're saying, though. The body language, bullpens, aggressiveness at pivotal moments, etc., it's all given (to me, at least) a vibe like the Rangers expect to win.
Swing for swing, base for base, it's been approximately even, but at key moments and over the course of 12 games (4-8) the Rangers have certainly given the appearance of being in control of the rivalry.
Which is my thesis here. The rosters favor the M's (as the team OPS+ and ERA+ currently show), but the M's aren't playing like it in the head-to-head games.
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Hope you can chime in often Sherm!