I thought I'd look at the Earl Weaver Clause in the official rule book. It's some windy baseball lore, for a day with no baseball.
Rule 5.11 (a) (2) reads as follows:
The Designated Hitter named in the starting lineup must come to bat at least one time, unless the opposing Club changes pitchers.
If you think about it - why would this clause even be necessary? Was there a rash of managers changing their minds about who their DH was going to be after they'd handed in the lineup card?
No. There was only Weaver, causing trouble. In August 1980, Weaver began writing one of his pitchers into the starting lineup as the DH. He would then pinch-hit for his "DH" as soon as his turn in the order came up. He did this in 21 of the Orioles final 24 games.
What was the point of this, you wonder? Well, Weaver was platooning at DH in 1980. If the Tigers started a RH pitcher, like Jack Morris, Weaver's usual DH was Terry Crowley who'd bat in the 6 or 7 spot in the order. But what if the Orioles knocked Morris out of the game in the very first inning, and brought in a LH reliever? Pat Underwood, or someone like him. Weaver would either be stuck with Crowley as his DH against a southpaw, or he'd lose one of his better hitters without even getting him into the game.
Weaver actually worried about these things. It's what made him special. Hence his solution, surely marvellous in its originality. With Morris on the mound for the Tigers, Weaver named his own ace starter, Steve Stone, as that day's DH. And when Stone's turn in the batting order came up (in the second inning, as it turned out), Crowley pinch hit for him against Morris and became the new DH.
How did this gambit work out for him? (This is the good part!) Weaver wrote a pitcher into the lineup as the DH 12 games in a row - and nothing happened. The Orioles never once knocked the opposition starter out of the game early. They managed to plate a single run, but no more, in just three of the 12 games (7 of which were played against a Toronto team that would lose 95 games that year.)
So, in the 13th game, Weaver abandoned his stratagem and started LH Pat Kelly as the DH (in the 2 hole) against Boston RH Steve Crawford.
And wouldn't you know it. Crawford lasted just five batters, and was replaced by a southpaw (Bruce Hurst). Hurst didn't last long enough to face Kelly, but Weaver resumed writing in a pitcher as his DH the very next day. He did this for 9 more games, and once more the Orioles never did put together a high scoring first inning.
So Weaver's clever idea never had any actual impact, it never did pay off for him in a game. It just produced some oddities at the end of the year. AL Cy Young winner Steve Stone started 12 games as the DH. Jim Palmer and Mike Flanagan both made 3 lineup appearances as the starting DH, Dennis Martinez, Tippy Martinez, and Scott McGregor one apiece.
And the rule was rewritten that off-season so that no one would ever do it again. Made a mockery of the game, blah blah blah...