koufax37 said:
You certainly don't move Xander off of SS or mess with Cecchini's development chasing a fraction of a win. You put in the ready replacement and hope he plays to at least his abilities and that a couple bounces work out in the meantime.
I agree with your math, and I'm not advocating a different strategy in this case to chase a "fraction of a win". I'm just pointing out the fallacy of assuming replacing an inferior player with a superior player, even over a short sample, won't be important.
To look at a replacement player vs. an "average" 3 win player, they will be about 0.02 WAR different per game. Over 2 weeks, about +0.25 WAR different. But what this means in real world terms is not "basically the same so it doesn't matter" (at least to me).
It's more like a breakdown as follows, with ballpark but realistic percentages for each outcome:
+3 or more WAR: <1%
+2 WAR : 5%
+1 WAR: 15%
0 WAR: 75%
-1 or more WAR: 5% (crappy players get hot, and good players get cold of course)
You're not chasing a fraction of a win. You're chasing a small, but real chance that the difference is actually worth a win or more, even over a short sample. There is plenty of handwringing over individual game lineup decisions, pitching changes, etc. that have a much smaller impact than 2 week roster decisions, particularly if the call-up is going to be a full-time starter.
You don't blow up a development plan just for a 20% chance at 1 win, and a 5% chance at multiple wins. But you also should have your eyes wide open when making these kind of decisions, and understand there actually is a chance they turn out to be important in the standings at the end of the year.
FWIW. I'm not saying Cecchini is a 3 win player right now, just using the number for the math.