Even though you are not actively trying to straighten the right arm you need to be ABLE to straighten your right arm (keeping your bent right wrist). In other words, if you come 'over the top' you have no room to straighten your right arm, but if you are correctly hitting the inside corner of the ball, you will be ABLE to extend your right arm as the SWING pulls it straight at follow through.
Split grip drills are a great way to feel this difference. Trying the extremes of OTT and "right field", you'll quickely get a sense of what I mean.
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"Support the On Plane Swinging Force in Balance"
"we have no friends, we have no enemies, we have only teachers"
Simplicity buffs, see 5-0, 1-L, 2-0 A and B 10-2-B, 4-D, 6B-1D, 6-B-3-0-1, 6-C-1, 6-E-2