Post beat writer Chico Harlan gave us the basics in the Nationals Journal blog:
When the Nationals placed Odalis Perez on the DL yesterday, they did so expecting to make the transaction retroactive to June 4, a day after the lefty's most recent start. But they encountered a slight problem. And as a result, Perez won't be able to return from the DL as quickly as they hoped.
Here's what happened.
To take Perez's place on the roster, Washington recalled Tyler Clippard (pitching tonight) from Class AAA Columbus. It's the second time this week Clippard was called up.
Turns out, a player cannot be recalled for a second time in 10 days or less except in the case of injury.
Therefore, Perez's injury -- for DL purposes -- needs to have occurred since Clippard last pitched for Washington.
Clippard pitched for the Nats on June 9, but the transaction that sent him back to the minors became official on June 10. As a result, Perez's DL stint is now retroactive to June 11.
Harlan has described this rule an obscure technicality, but this is actually a totally logical and important rule that prevents teams from chruning through guys like roto league owners. If it wasn't for this rule, teams could, theoretically, carry 4 extra position players and just send their whole starting rotation down to the minors after every start. Or, if your bullpen gets burned up and you need 2-3 extra guys in a pinch, no problem, just open up the roster spots by sending down the starters who aren't going to be available to pitch anyway.
It's really quite simple and routine. If Perez is out for 15 days retroactive to June 4, you need someone to fill 2 starts. That's Clippard, so he's up for 2 starts and can't go down between starts, period.
How do we know that this wasn't just a situation where something else happened, like maybe Perez underestimated the injury, and the team got caught in an unavoidable bind? Based on the sequence, as reported on MLB.com and elsewhere, it's clear that Bowden just didn't know the rule:
6/4: Perez leaves the game with tendinitis. At this point it is reported that he will miss one start, but it's not stated whether he'll need DL time or miss more time than that.
6/9: Clippard pitches in Perez's spot. Perez is still on the active roster, presumably because the team is waiting to see if he's going to heal fast enough to miss only one start.
6/10: Clippard sent down, Belliard takes his spot. Perez is still on the active roster, as the team still apparently is hoping Perez will be ok for his next start. However, the team never listed Perez for this start in their probables, and presumably there was never a time when they were confident he'd make that start.
6/12: It is announced that Perez is still too hurt to pitch and that he will go on the DL. IMPORTANT: At the same time, the team announces that Clippard will be called BACK UP to take Perez's spot. At this point, it should be clear to the team that by choosing Clippard to take the start, they will NOT be able to put Perez on the DL to June 4 retroactively, because it hasn't been 10 days since he was last sent down.
6/13: Team puts Perez on the DL, retroactive to June 4, apparently unaware that when they call up Clippard later that day, it will cause Perez to lose his retroactivity.
6/14: Clippard is called back up. Perez loses his retroactivity. Late that night, Chico explains it all to us, after the team explained it to him, presumably after the league explained it to Bowden.Keep in mind, it's not so much that losing a start or two of Tyler Clippard or Odalis Perez is such a tragedy. They're both pretty bad. The point is that Bowden is theoretically a professional who needs to make maybe 1-2 decisions a day, and he can have as many people as he wants check his homework.
I think the Nationals Journal commenter "I hate walks" put it nicely: "What if you paid someone to mow your lawn and they mowed over your flowerbed. Do you shrug it off and say 'Hey, it's just MY lawn not the White House. It doesn't really matter that much.' Or do you get upset with the idiot operating the mower who really should have known better?"