This cockeyed idea has many fathers in my brain, but the biggest calling siren stems from my limited experience at looking at American League boxscores. In short it's like... where the hell are all the subs? Do any of these guys ever get to play?
An AL boxscore very often just has nine names, that's it. Making a NL box look like a T-maze. And gone is the fun and intrigue of roster players flying in and out and up and down, All because (the AL's original intention) was to make it so pitchers didn't have to hit.
Well...here we go:
The eight position player starters on any given night should be allowed to leave the game (offensively or defensively) and yet re-enter at a later time. Just one usage. Of course the re-entering starter would have to take his original place in the batting order, no matter what fielding position he takes or re-takes. And the sub who got subbed would lose game eligibility from then on.
This would, in effect, create four or five highly usable 'platoons' for the manager, and he could of course vary the twinning each game. And wait for what he thinks is the right time. It would especially help out the catcher situation, and that best illustrates what I am trying to create here.
Wouldn't it be nice, for instance, if in a blow out contest, MM could lift Yadi, to save his legs and squatting. He could do it early, fifth inning stuff even. Should the game reverse course and become close again and Matheny thinks, damn, I wish I could put Molina back in. Well, per the above, he CAN.
And the idea of maneuvering Jose Martinez under this system should have any current Cardinal fan's mouth drooling.
OK, even if you buy that this would make the games more exciting and deliciously complex, you may ask... how does this address the pitchers not hitting situation? I left it out at the beginning above, but the simple answer is: the starting pitcher is also, ta-da, a starting position player. Meaning one of his at-bats (manager's choice) can be taken by a pinch hitter, and the SP can still return to the mound to do his hurling thing. Just ONE. And it would not apply to any subsequent relief pitchers who take over mound duties.
With the added 'if you act now' bonus wrinkle, if the manager chooses to exercise the PH option of the SP's very first at-bat, then that pinch-hitter would still retain his substitution eligibility later in the game. No super early bench bat squandering.