**Note: **The comic below comes from the hilarious website xkcd.com. If you have not visited them please do so. This comic is also included on “The Book” blog. We offer both sites the most humble of glove slaps and thank them for entertaining and educating.

Among sabermetric enthusiasts there are several canonical references. Perhaps the most revered is “*The Book: Playing Percentages in Baseball*” by Tom Tango, Mitchel G. Lichtman and Andrew E. Dolphin. At the the website of “The Book”, Tom Tango and Mitchel Lichtman both continue to post blog entries on sabermetric topics. On Monday July 25th, Lichtman posted on a topic most Orioles’ fans have been fretting over: Nick Markakis’ lack of power.

Nick Markakis averaged 17.7 HR per 600 PA [plate appearances] in his first 4 years in baseball. Since then (2010 and 2011), he has averaged 11. There has been much talk about him “losing his power.” Now, obviously that is not a huge drop in power, but let’s look at this from a statistical perspective and we’ll use a little Bayesian inference as well. Markakis had 2660 PA in those first 4 years, with a HR rate of .029 per PA. One standard deviation in HR rate in 2660 PA, by chance alone, is around .0026 (assuming a true rate of .0183). Let’s say that his true HR rate over his career was actually .022, or 13 HR per 600 PA. His performance in the first 4 years would be around 2.7 SD above his true talent HR rate, by sheer luck alone. That is going to happen around 1 out of every 385 times.That may be a small number (1/385), but the fact that we are cherry picking Markakis (or some other player) means that there are lots and lots of players who did NOT seemingly lose their power over a similar time period. In other words, with all the players we can look at, a few of them will, by chance alone, significantly under-perform their true talent HR rate (or any other stat) for no articulable reason whatsoever …. I’m just saying that it should come as no surprise whatsoever that a few players would seriously under-perform after 4 full years of baseball, simply because during those first 4 years, they just got lucky.

Co-author Tom Tango weighed in trumpeting the need for scouting, particularly scouting that goes against what the empirical data might suggest.

There is exactly one way to improve the model [our expectation of Markakis’ future power]: break down the mechanics of the player. … The solution can only come down to scouting.

Unfortunately, I am not a scout. I have not even played baseball since I was ten. There are few people less qualified to break down the mechanics of Markakis’ swing than myself. However, I am capable of identifying trends in data that might suggest a change in Markakis mechanical approach over the years. This week in By the Numbers we will painstakingly look at different aspects of Markakis’ declining HR rate. The main tool we will employ is Greg Rybarczyk’s Home Run Tracker which is now hosted at ESPN Stats and Information. Home Run Tracker determines the “true distance” of a home run by considering the impact of the altitude, temperature and wind on the home run. Home Run Tracker also bins each home run into one of three categories: **Just Enough**, **No Doubt**, and **Plenty**. A “**Just Enough**” home run means the ball cleared the fence by less than 10 vertical feet, or that it landed less than one fence height past the fence. A “**No Doubt**” home run means the ball cleared the fence by at least 20 vertical feet and landed at least 50 feet past the fence. These are the really deep blasts. A “**Plenty**” home run accounts for all other home runs. First lets look at the true distance and location of all of Markakis’ MLB home runs.

There is one dramatic trend in the above graph that points to a change in Markakis’ mechanical approach circa 2009: the lack of opposite field (LF) home runs from 2009 to present. I am not the first one to notice this. Camden Crazies’ Daniel Moroz covered this in a post at Fangraphs in 2010. Both the graphics Daniel showed in that article and the graphic above points to some type of change in Markakis’ physical makeup and/or approach that a scout could possibly diagnose. While I have not run the Bayesian inference numbers, I find it unlikely that we would expect even a cherry picked player to post an opposite field HR rate of .0015 (3/1950) over his last 1950 plate appearances after posting an opposite field HR rate of .0087 (17/1950) in his previous 1950 plate appearances. If I am wrong I apologize to Mitchel Lichtman for not running the numbers before stating my claim and not fully appreciating all aspects of Bayesian inference.

The type of home runs Markakis hit also provide us with insight. The graph below shows how many of each type of home run Nick hit in each season.

A large portion of Markakis’ opposite field home runs in 2007 and 2008 were binned in the “Just Enough” category. It is very possible that some physical change in Markakis in 2009 (even simply aging) caused him not to be able to hit fly balls that carried “just enough” to the opposite field. Also, and perhaps because of this, Markakis developed a different approach at the plate that did not employ going the other way. Of course both of these statements are pure speculation. As Tom pointed out, without scouting its impossible to know. It is also important to note that Markakis was lucky with his home run rate in 2007 and 2008. Most of the “Just Enough” home runs would not have been home runs if they were hit in the more extreme ballparks in the AL or in more extreme weather conditions (SafeCo, Comerica, etc.).

My speculation, and again given my background it should be taken with a grain of salt, is that Markakis was pretty lucky in 2007 and 2008. Instead of being an almost an ~18 HR / 600 PA, he was actually a 14-15 HR / 600 PA player. However, in 2009 some mechanical change in his physical makeup or his approach caused him not to hit HRs to the opposite field. This mechanical change combined with his true 14-15 HR / 600 PA talent level has depressed his HR rate to its current 11 HR / 600 PA level. It is important to note, this explanation still does not elucidate Markakis’ 2009. In 2009, Nick only tallied one opposite field HR while posting very few “Just Enough” HRs and a career high in “No Doubts”. I don’t have any additional insight on this season and I’m not sure any more is needed. Markakis is signed for the next three years and our best expectation for his home run rate is 11-12 HR / 600 PA going forward. Explaining 2009 is interesting but most likely simple fodder considering his contract and the future of the Orioles.