I thought I'd actually do a little homework instead of just assuming Wilson and Short Rest Lee are better than Hunter and Extra Rest lee.
There are numbers and stuff after the jump.
This year, pitchers on three days of rest have had an ERA 13% higher than they do on four days of rest. If you expand that number, it actually goes down. If you go back over the last five years, it's been 12%. If you go all the way back to 2001, it's been 10%. There have actually been years where pitchers on short rest have pitched BETTER.
For this, I'm going with the five year number: 12%.
This season, Cliff Lee has had an expected Fielding Independent Pitching ERA of 3.24; that's a decent forward-looking estimate of his ERA in front of a neutral defense (the Rangers are better than that, but all three pitcher should, in theory, have the same defense).
Tommy Hunter's xFIP this season has been 4.74, which may be overrating him. xFIP regresses a player's home run rate on fly balls to league average, but it's entirely possible Hunter is serving up way too many meatballs. His FIP without the regression is 5.02.
C.J. Wilson's xFIP 4.22 this year, and he's an opposite case of Hunter. The truth is somewhere between pitchers having full control of their HR/FB rate and having none, and Wilson may be closer to the former. His un-regressed FIP is at 3.59 this season.
So then, if we work with that 12% rate, Lee's xFIP expands to 3.63. If you combine that with Wilson, you get a 3.93 expected ERA (without markedly good or bad luck or defensive performance) from your starting pitchers over the two games. That's up against a 3.99 ERA with Lee and Hunter. So, it's close, which is probably a bit reassuring if you're worried about going to Hunter.
We can go a little deeper than that, however. Lee averages 7.21 innings a start for Texas, Wilson 6.22 and Hunter 5.81. When you fill in the remaining innings pitched with the Rangers' bullpen in 2010, that gives you an xFIP in games Lee starts of 3.76 with short rest adjustment (3.58 without), against 4.24 for Wilson and 4.58 for Hunter. That takes you to 4.01 in the Lee/Hunter combo and 4.00 in the Short Lee/Wilson combo. Why does it actually make it closer? Because the Rangers' bullpen has been really good in 2010. However, bear in mind that the earlier a Rangers' pitcher leaves, the more of the weaker points of the bullpen need to be used.
With the Rangers' RPG (4.87) in 2010 combined with that pitching, that would give the Rangers a .570 pythagenpat record with the Lee/Hunter combo (obviously it would be lower against the talent the Rangers will play in the first round, we're just comparing the pitchers). The Short Rest Lee/Hunter combo gets a .572.
Admittedly, we're looking pretty close at this point, but, remember, that's assuming Hunter has been completely unlucky on his home run rate and Wilson has been completely lucky. The more you believe in their actual HR/FB rates, the more it begins to favor the Wilson/Lee combo. If you switch from xFIP to FIP, the Lee/Hunter combo goes to a 3.75 expected ERA over the two games (again, bullpen included) vs. 3.41 for the Lee/Wilson combo (short rest for Lee). Now, the difference is a bit larger. That's a .619 pythag record for the Hunter/Lee games as opposed to .658 for the Lee/Wilson games; the difference between a 100 win team and a 107 win team.
That's all if you assume Lee can't pitch better than the average starter on three days rest over the last five seasons. If you assume he can -- he is an efficient pitcher who may be able to keep his work down in game one before going to an excellent bullpen -- it favors going to him in game four even more.
Admittedly, this is a lot closer than I thought it would be. If nothing else, it makes me feel a little better about Hunter going if the Rangers do that. Also, you could look at this much deeper than I have, and if someone wants to, I ask them to please do so. The more information the better. But the fact of the matter is that Tommy Hunter has just not been a good pitcher at all in 2010, and the Rangers have three good pitchers. One of them is one of the absolute best pitchers in baseball. Going to those guys as much as they can handle without being worse than Hunter makes sense, even if the edge it gives them is small. And, personally, I think the edge is at least small.
Note: I started working on this before Adam Morris put up his take at Lone Star Ball. Even if I disagree with his conclusion, it's a thoughtful take that should absolutely be read.