How many wins would Halladay add?

Lynn Henning reports today that the Tigers and Blue Jays discussed Roy Halladay and the price would be Rick Porcello, Ryan Perry, and Casey Crosby. Essentially the top 3 arms drafted and signed in the last 2 years by the Tigers. It’s a very steep price that had me balking on first blush. But after a deeper dive and this trade looks a lot more interesting.

We know that Halladay would replace Porcello in the rotation. Let’s assume that there are 13 turns left in the season for either pitcher. Halladay averages 7 1/3 innings per start meaning he’d throw another 95 innings. ZiPS projections have him throwing 84 more innings. We’ll split the difference and call it 90.

Porcello doesn’t pitch as deep meaning he’d likely go about 5 1/3 innings per start or about 70 innings. The bullpen would presumably pitch the rest of those innings.

Halladay has  FIP of 2.74 this year and ZiPS has him at 3.13 the rest of the way. Porcello has a FIP of 5.33. We don’t know exactly which relievers would pick up those other 20 innings, but we’ll assume they have a FIP of 4.50. Multiplying it out, we could estimate that Porcello+pen would surrender 51 runs. Halladay picking up those innings would surrender 31 runs over that same span. That’s roughly a 2 win swing over 62 games which is pretty significant.

But the Tigers are a fairly low scoring team with a fairly solid pitching staff and defense, in other words a lower run scoring environment team. Beyond the Boxscore points out that context matters in these things. They used PythagenPat, and I’ll use Pythagorean but the same general principle applies. Right now the Tigers are a .537 or 87 win team based on their runs scored and runs against. They are pretty close to that based on actual record as well. They average 4.66 runs scored and 4.35 runs allowed. If you reduce their total runs allowed by 31 21 (edit: I screwed up the math…sorry) the team becomes a .553 or 89.7 win team.

Now 87 wins stands a pretty good chance of winning the division and getting in the playoffs, but it is far from a certainty. A 90-91 win team will have a very, very good chance at taking this weak division. With that sort of context it almost makes it harder to turn down this deal than it is to accept it.

The price is steep in terms of prospects and value. Porcello won’t be a free agent until 2015. Expecting him to be as good as Halladay is unfair, but expecting him to be an above average pitcher for cheap for 5 more years is reasonable and makes him valuable. Crosby has the stuff and stats that make prospect lovers drool, and he’s a lefty. Perry is a pen arm, quite possibly a good one, but not terribly difficult to replace.

The upside of getting Halladay is tremendous though, and they’d have him for another season (provided Halladay doesn’t invoke his right to demand a trade in the offseason) and he could be flipped at the trade deadline next year if the team isn’t in contention or at the very least he’d net 2 first round picks if he signed someplace else.

I’m not anxious to see Porcello or Crosby go anyplace, but this would be one of only a handful of scenarios where I would be willing to let them go.