Talking Chop

As we are all painfully aware, many Braves hitters have started the year in slumps. Fortunately, some of the slumpers have already begun to emerge (Melky, Glaus) and others undoubtedly will soon, provided they are healthy (Escobar, Chipper). The two hitters who have yet to show any signs of life this year are Matt Diaz and Nate McLouth. While Diaz has been worse, McLouth's slump is probably more worrisome. Why? Because he was equally bad in Spring Training and at the end of last year. Even if you discount ST, here are Nate's numbers for the last quarter-season or so:

Those are some ugly, ugly numbers. Given that they cover about a quarter-season, you might be tempted to dismiss McLouth as injured, terrible, or both. But remember that 158 PA is still a fairly small amount. Let's compare the numbers from his slump to what his career averages look like when pro-rated to the same number of PA:

I've added two extra columns that are crucial to understanding the nature of McLouth's slump: Batting average on balls in play (BABIP) and ground-ball rate (GB%). As you can see, Nate's BABIP has been abnormally low during his slump, due largely to bad luck. Though other factors can cause a lowered BABIP, they cannot cause nearly this magnitude of a discrepancy--nobody hits .180 on balls in play without a lot of bad luck (except maybe Tommy Hanson).

Nate's GB% has gone up a fair amount during his slump. Since ground balls are worse than fly balls (especially in terms of extra-base hits), the added number of ground balls would also make Nate's numbers worse. 

You may also have noticed that Nate has been putting far fewer balls in play lately, as his walk and strikeout totals have both skyrocketed during the slump. This has an overall negative effect, since you can't get extra-base hits if you don't hit the ball fair. Perhaps Nate is actually working the count too much.

So we have 3 possible explanations for Nate's slump: an abnormally low BABIP (caused mostly by bad luck), a slight increase in ground-ball rate, and a change in plate discipline. After the jump, I break down each of these 3 factors to see just how much of Nate's slump is caused by each one.

Like a scientist would do, I did my best to isolate each of the 3 variables. In the discussions below, I determine what McLouth's numbers would look like if only 1 of the 3 variables reverted to normal. So for the "Low BABIP" section, I used Nate's career BABIP figures but the GB% and plate discipline stats from his slump.

Overall, we're looking to account for a loss of 15 hits and 25 total bases, as well as about 100 points of AVG, 50 points of OBP, and 170 points of SLG.

Low BABIP

I looked up Nate's career BABIP for ground balls, fly balls, and line drives. I then multiplied those numbers by the GB/FB/LD splits from his slump to see what his BABIP, AVG, and ISO (isolated power, or SLG minus AVG) would be if his BABIP were normal. Here is what I found:

With normal BABIP rates, McLouth would have had 8 more hits and 12 more total bases over this period. That equates to a 150 point increase in his OPS. That is a huge difference, although the resulting .720 OPS is still underwhelming. This should give Braves fans (and McLouth) some comfort, as it indicates that he's not playing nearly as badly as his current line suggests. He does clearly need to work on a few things, though.

There is some question of just how much of this abnormally low BABIP is attributable to luck, and how much is attributable to McLouth himself. For instance, if Nate is not hitting the ball as hard as normal, or if he has lost some foot speed, that would naturally reduce his BABIP. Still, I'd say that at least half (and probably much more) of the drop in BABIP is due to bad luck. 

High GB%

For this section, the only thing I changed was the relative proportion of McLouth's GBs, FBs, and LDs, for which I used his career rates (37% GB / 44% FB / 19% LD).  This meant that instead of 39 GBs, 36 FBs, and 16 LDs, I was assuming Nate had hit 34 GBs, 40 FBs, and 17 LDs. Here are the results:

McLouth's increased GB% has cost him only 1 hit, 4 total bases, and 39 points of OPS. This is a noticeable amount, but not very large when compared to the effects of his low BABIP.

Change in Plate Discipline

For this section, I kept Nate's batted-ball rates and BABIP numbers at his slump levels. The only change was to convert the 7 extra walks and 10 extra strikeouts into balls in play. Thus, instead of 39 GBs, 36 FBs, and 16 LDs, I assumed that McLouth had hit 46 GBs, 43 FBs, and 19 LDs. In that scenario, Nate's numbers would look something like this:

If Nate had maintained his career walk and strikeout rates during his slump, he would have gained about 5 hits and 8 total bases. Though this would have increased his AVG and SLG, it  would also have lowered his OBP. Overall, he'd gain 31 points of OPS, but since OBP is more important than SLG, the actual benefit would be somewhat less than it seems. Again, this is a measurable difference but not nearly as large as the difference caused by his low BABIP. 

Conclusion

Overall, we can safely say that each of the 3 factors has had some effect on McLouth's slump. The abnormally low BABIP is clearly the biggest factor, however. Here's a breakdown of how much of the Nate's lower stats during the slump can be explained by each factor:

When you compare the total differences explained by these 3 factors to the actual differences listed in the second table, you see that these 3 factors explain about 99% of Nate's slump. About two-thirds of the slump is due to an abnormally low BABIP (most of which is caused by bad luck), about one-fifth is due to a high GB%, and about one-eighth is due to a change in plate discipline.

What does this mean? I'd say there are 4 keys to Nate's performance going forward (ranked in order of importance):

1. Get better luck (beyond his control, but crucial)
2. When putting the ball in play, hit fewer ground balls
3. Put the ball in play more
4. If injuries (or mechanical flaws) are reducing his bat speed or foot speed, allow them to heal (or fix them)

If Nate can do all this, he'll be back to being the very good player he used to be (though not an all-star; he was never really all-star caliber). I have no idea when (or even if) any of this will happen, but let's hope it happens soon. We could use some more pop from our outfielders.