The Saber's Edge: How to Judge Breakouts vs. Hot Streaks

This week, I will look at the four core stats to find out whether the breakout is real.

First off, in this sabermetric friendly age, there are too many stats to know, and one can get lost in the volume. Truthfully, I find a few of these stats the most telling of a hitter … they are the ones scouts look for: Power. Eye. Ability to square up a ball. Approach.

A hitter moving from a .250 AVG to .300 AVG could be for several reasons. The player could have cut his strikeout rate. Or began hitting the ball harder. Or a few groundballs could have gotten past the infield defense for some weak singles. The following is a look at the few traits I start with when looking at a changing player.

Batting Eye

For years, a player's batting eye was limited to strikeout rate, walk rate or some combination of the two. Nowadays, our fancy stats can give more details by telling us if the batter was swinging at pitches in or out of the zone.

Of these various swing rates available, the one to concentrate on is Outside Swing Rate (O-swing%), which correlates nicely with the hitter's walk rate (BB%). For every 1 percent point drop in outside swing rate, a hitter should expect a 1.3 percentage point increase in his walk rate.

Note: While several places have swing and contact rates, I usually use these player tables at FanGraphs.

For example, here are the 10 players who have seen the largest change in their O-swing% and how their BB% has changed (min 300 PA in each of 2015 and 2016).

All 10 hitters have seen their walk rate improve.

Remember, don't just go to a player's walk rate and look for improvement. The higher walk rate could be from the hitter being intentionally walked more. The classic example of this occurrence was Albert Pujols.

The good correlation can be seen in the top-10 hitters who improved their contact rates from 2015 to 2016 (min 300 PA each year).

This trait shows a batted ball's potential trajectory. Historically, none of this data was available until 2002 when stringers began lumping batted balls into groundballs, line drives and fly balls. While there has always been some disagreement between when a line drive becomes a fly ball, the labeling has been fairly consistent with the historical splits being 45 percent GB, 20 percent LD and 35 percent FB. Instead of memorizing all the values, it is simple to just remember that line-drive rate will generally remain the same and a 1 percentage point change in GB% means the player's FB% will then change by 1 percentage point in the opposite direction.

Batting average fluctuates depending on the batted ball type. Ground balls yield a .239 AVG. Line drives have a .685 AVG. Finally, fly balls have a .207 AVG since most non-HRs are caught.

Hitting the ball in the air doesn't do a player any good if the ball can't go for a home run. Take Dee Gordon and Billy Hamilton, for example. Both are extremely fast. Gordon has put the ball on the ground 58 percent of the time in his career for a .291 career average. Hamilton hasn't put his speed to use while hitting on 43 percent of his balls on the ground and his a .244 career AVG. Both have almost the same batting averages on groundballs (Gordon's .292 and Hamilton's .290) and fly balls (Gordon's .147 and Hamilton's .125), so Hamilton could perform better.

Unfortunately, no conclusions can be drawn from a batted ball profile until power is added.

Raw Power

The final aspect to take into account is power. My statement above on StatCast remains true and this discussion may be moot soon with better data. Until then, isolated power (ISO) is a nearly perfect way to measure power level. When doing some batted ball comparison at the Hardball Times, I found it holds up just fine when compared to other Solid Contact metrics. The hitter's hard-hit ability is separated from the lucky nature of singles.

This hitter trait needs to be combined with a batted ball profile to help finally determine a hitter's true talent level change. Taking the Gordon and Hamilton example again, the average AVG for a hitter with below league average power and high groundball-ball rate is .266 (Gordon clone). If the hitter puts the ball in the air more than league average (Hamilton), the average AVG is .254.

Daniel Murphy Example

Taking all four of the traits and looking for a player who may have turned the corner, I will go with Daniel Murphy. In 2015, he hit .281/.322/.449 while this season he is hitting .356/.395/.623. Starting with his O-swing, it is basically unchanged (32.6 vs. 32.4 percent) and so is his walk rate (5.8 vs. 5.3 percent). Now, his Contact% is down about 4 percent, which almost perfectly explains the increase in K% from 7 to 10 percent, which should suppress his AVG some. The first major change came with his batted ball mix with his GB% going down 8.5 percentage points and his FB% up the same amount.

Finally, his ISO (power) is up almost 100 points going from .168 to .267. The extra power and fly-ball nature has led to a career high in home runs. The one area I could see him regress is his batting average. I've already noted his K% should bring down his AVG and also his higher FB% should do the same. Now that he is hitting the ball harder, this increase could offset the negatives and possibly become a positive influence on his AVG, but not a 70-point improvement. For Murphy, the breakout has some merit, but I am little worried his AVG could sink some.

When trying to find out if a hitter is breaking out, an owner needs to dig smartly to see what could be behind the change. The key is to see if the player has changed his approach in some aspect of the game like knowing what a called strike is, making hard contact with the pitch and hitting it at the desired angle. If none of these aspect change, how can a batter be turning the corner? They are probably just spinning their wheels and will be back to their old ways soon.