Do Catchers Matter?

Wednesday, June 11 2003 @ 07:32 AM EDT

Contributed by: Craig B

Batter's Box reader, poster and econ-whiz Mike Moffatt has prepared a great article on the Jays' 2002 catchers, measuring their impact on the pitching staff. We are happy to bring this to you at Da Box.

The thrust of Mike's piece is that Ken Huckaby's gaudy catcher's ERA is a result of who he was working with, as opposed to what he was doing. Mike's method is something that would make an interesting study is broadened, and might tell us something about whether catchers really have an impact on the pitchers they hook up with.

If you have an article or other piece, feel free to run it by me (tybalt4@yahoo.com); we're delighted to employ pinch-hitters here (this is an NL-style website, not an AL-style website).

Over to you, Mike...

Catcher's ERA and the 2002 Blue Jays
Mike Moffatt

Over the last few months the topic of Catcher ERA has come up from time to time both on Batter's Box and alt.sports.baseball.tor-bluejays. A few people have argued that Ken Huckaby, although a lousy hitter, should remain one of the regular catchers on the Blue Jays due to his low Catcher ERA. I claimed that the comparison wasn't relevant because the two catchers may have caught different pitchers, so the catcher who primarily caught Roy Halladay should have a better CERA than the catcher who primarily caught Scott Cassidy.

Unfortunately, nobody ever bothered to find out how each pitcher performed when matched up with each catcher. I decided to take a look at the stats, with the help of Astros Statistical Software. I examine 14 different pitchers who had at least 10 innings pitched against 2 or more catchers.

The problem with this kind of analysis is the small sample sizes involved. Even though a pitcher might have an ERA a full 200 points lower with one catcher than another this may just be random chance as a pitcher/catcher pair may have only worked together for 15 or 20 innings. The fact that the offensive performance of opposing teams varies widely will also introduce a bias. If Darrin Fletcher caught Luke Prokopec for a couple games in Detroit, and Ken Huckaby caught him for a couple of games in Texas, then Fletcher will probably look like the much better catcher. So take anything in here with a huge grain of salt.

I look at four metrics of determining pitcher performance. The first three are the standard Home Runs Per 9, Walks Per 9, and Strikeouts Per 9. The last column, DERA is DIPS ERA or Defense Independent Pitching Stats ERA, created by Voros McCracken. To learn more about DIPS ERA see this discussion at Baseball Primer. I used the formula posted by Vinay Kumar on the bottom of the page.

Now to the results:


Brandon Lyon       IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  27.3  1.65  2.31  4.29  5.32
Tom Wilson       26.3  2.74  3.76  4.11  7.25


Brandon Lyon gave up a lot more homeruns and walks for Tom Wilson than he did for Darrin Fletcher.

Chris Carpenter    IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  18.0  3.00  5.00  8.50  7.08
Ken Huckaby      50.3  0.72  2.86  4.83  4.17


Chris Carpenter pitched much better for Huckaby than he did for Fletcher. Carpenter gave up more walks and homeruns when Fletcher was catching but he also struck out more batters.

Cliff Politte      IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  10.0  1.80  3.60  8.10  5.22
Ken Huckaby      32.7  0.55  4.13 10.18  3.23
Tom Wilson       14.0  0.64  0.00  6.43  2.74


Politte was mediocre for the 10 innings Fletcher caught him, but was terrific for Huckaby and Wilson. In 14 innings he did not walk a single batter when Wilson was catching, but he had a much higher strikeout rate when Huckaby was behind the dish.

Corey Thurman      IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  15.3  0.59  7.65  5.29  5.62
Ken Huckaby      25.0  3.24  5.40  7.56  7.93
Tom Wilson       22.7  0.40  6.74  9.12  4.02


Corey Thurman was incredibly prone to the long ball when Huckaby was catching, who he had a 7.93 DERA with. Unlike Politte, Thurman had a much higher strikeout rate with Wilson than Huckaby.

Esteban Loaiza     IP  HR/9  BB/9   K/9  DERA
Ken Huckaby      98.3  1.01  1.92  5.22  4.19
Tom Wilson       45.0  1.40  2.60  5.00  4.88


Esteban Loaiza gave up fewer homeruns and walks and had more strikeouts for Huckaby than Wilson, with a difference in DERA of 0.79.

Felix Heredia      IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  15.7  0.00  4.01  7.45  3.02
Ken Huckaby      14.7  0.61  1.84  4.29  3.87
Tom Wilson       20.0  1.80  6.75  4.05  6.77


Felix Heredia pitched well for Fletcher and Huckaby, but was awful when pitching to Wilson.

Justin Miller      IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  13.3  0.68  8.80  5.41  5.61
Ken Huckaby      71.3  1.26  5.43  7.07  5.24
Tom Wilson       17.7  0.51  5.08  2.03  5.48


Justin Miller performed about the same for each catcher who was assigned to him. His strikeout rate was much higher with Huckaby than Wilson, but unfortunately so was his home run rate.

Kelvim Escobar     IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  12.3  0.00  6.59 10.24  3.25
Ken Huckaby      38.0  1.18  4.74 10.18  4.27
Tom Wilson       25.7  1.75  4.90  9.11  5.16


Escobar was much better pitching to Fletcher than he was to Huckaby or Wilson. Unlike Miller, Escobar gave up far more homeruns when Wilson was catching than Huckaby.

Luke Prokopec      IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  25.7  1.05  3.85  5.95  4.66
Ken Huckaby      20.7  3.04  1.30  5.22  6.85
Tom Wilson       25.3  3.20  3.91  4.27  7.85


Prokopec also pitched much better for Fletcher than he did for the other two catchers. His control seemed to elude him when he pitched for Wilson, as he had a much higher walk rate and a lower strikeout rate for Wilson when compared to Huckaby.

Pete Walker        IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  14.0  0.64  1.93  6.43  3.47
Ken Huckaby      62.0  1.31  3.63  4.94  5.21
Tom Wilson       56.3  1.12  3.36  5.28  4.79


Walker was better in all three categories when pitching to Wilson than he was pitching to Huckaby leading to a difference of 0.42 in DERA.

Roy Halladay       IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  33.7  0.80  1.60  7.21  3.41
Ken Huckaby     149.7  0.36  2.40  5.53  3.43
Tom Wilson       56.0  0.16  2.57  7.88  2.73


This absolutely floored me. Roy Halladay was a much better pitcher when matched up with Tom Wilson, as his homerun rate was much lower when Wilson was catching. Halladay still pitched very well for Huckaby, who caught Halladay almost 100 more innings than Wilson did. I believe this is why Ken Huckaby had a much lower CERA than Tom Wilson in 2002.

Scott Cassidy      IP  HR/9  BB/9   K/9  DERA
Ken Huckaby      28.0  1.61  3.21  6.75  5.13
Tom Wilson       24.3  2.22  5.93  5.56  7.47


Scott Cassidy was a much better pitcher when Huckaby was behind the plate rather than Wilson.

Scott Eyre         IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  21.3  1.27  6.34  6.34  5.44
Ken Huckaby      15.0  0.60  3.00  7.80  3.45
Tom Wilson       27.0  0.00  3.00  7.67  2.70


On the other hand, Scott Eyre did not perform well with Huckaby as a catcher and was even worse with Fletcher. Eyre did not give up a homerun in the 27 innings Wilson caught him, giving Eyre a much better DERA with Wilson as compared to Huckaby.

Steve Parris       IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher  16.7  1.08  4.31  3.77  5.27
Ken Huckaby      44.7  1.41  4.23  6.04  5.26
Tom Wilson       14.0  2.57  3.86  7.07  6.11


Steve Parris did not pitch well when matched up with any catcher, but pitched worst when matched up with Wilson. Parris gave up 4 homeruns in 14 innings when Wilson was catching.



That's all fourteen pitchers. To see how the catchers performed as a whole, I used the "Matched Innings" method from The Diamond Appraised. I have no reason to recommend this method of averaging over any other one, but it's probably the best known so I decided to use it. Using Wright's methodology, there are 163 matched innings over 10 of the 14 pitchers:



Matched Innings    IP  HR/9  BB/9   K/9  DERA
Darrin Fletcher 163.0  0.78  4.45  6.59  4.37
Ken Huckaby     163.0  1.34  3.34  6.53  4.84
Tom Wilson      163.0  1.17  3.95  6.40  4.74


Matching innings this way leads to Huckaby having the highest Catcher DERA on the team. I'm quite certain that a different method of matching would show Wilson having the highest Catcher DERA. Given the sample sizes, it's pretty difficult to determine anything from this. From what little data we have, I do not see any indications that Huckaby handled the pitching staff any better than Wilson did.

I'd love to hear your comments on the matter.

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