Victor Martinez' Power Surge and Regression

In his last 7 games, Victor Martinez has hit 4 home runs, bringing his total to 8 HR on the year.  V-Mart ranks tied for 14th in all of baseball and 7th in the American League in home runs.  He leads the Tigers by 3 over Miguel Cabrera.  This is all surprising because Victor Martinez isn't really a home run hitter.  The most home runs he has hit in any given year was 25 in 2007 and he's on pace to pass that mark by about 13-14.  Through his first 33 games, here is how many home runs V-Mart has hit in each year:

Year	Home Runs
2004	6
2005	2
2006	5
2007	5
2008	0
2009	6
2010	3
2011	4
2013	1
2014	8

2008 was an injury-shortened year and he missed all of the 2012 season also due to injury.  There are a couple of 6's and 5's in there, so he has come close to this pace in the past to start the year.  It's worth noting that Martinez was still was catching often through the 2010 season, so the grind of catching could have slowed down his pace in the past.  However, even though he's mostly DHing now, he is much older, so it's still unlikely that he'll maintain his current pace.  However, it's still fun to look at the numbers.

Year	HR%	HR/FB
2004	3.9%	11.6%
2005	3.2%	13.4%
2006	2.5%	9.3%
2007	3.9%	13.2%
2008	0.7%	2.5%
2009	3.4%	12.5%
2010	3.7%	10.7%
2011	2.0%	7.3%
2013	2.1%	7.2%
2014	5.8%	17.0%
Career	2.7%	10.2%

The HR/FB ratios are taken from FanGraphs.  

Martinez has hit 0.242 home runs/game, on pace for 39 home runs given 162 games.

Martinez has a 5.8% HR rate, on pace for 38 home runs given 650 plate appearances.

Martinez has a 17.0% HR/FB ratio, on pace for 38 home runs given 221 fly balls*.  

*V-Mart is on pace for about 221 fly balls in 2014.  He has a 39.2% fly ball ratio, an 8.7% walk rate and only a 4.3% strikeout rate and 0 hit by pitches.  

Batted Balls = plate appearances - walks - strikeouts - hit by pitches.  

Given 650 plate appearances, that's 57 walks and 28 strikeouts.  That's 650-57-28  = 565 batted balls.  565 * 39.2% = 221 fly balls (rounded).  

We can start here with the regression.  V-Mart's strikeout rate is the lowest of his career.  Over his prior 3 years (2010-2013), his strikeout rate was at 9.2% and career-wise it's at 10.7%.  This year, it's less than half of that.  His strikeouts have been trending downward, but it's unlikely it'll remain at his current low pace.  Let's say he finishes the rest of the year at 8.5%.  Given 650 plate appearances, that's (650-138 = 512 * 8.5% = 44 more strikeouts for a grand total of 50.  

Martinez' walk rate over his prior 3 years is at 7.8%.  His career mark is at 9.3%.  His current 8.7% rate is right in the middle.  It's reasonable that he can keep this pace for the rest of the year, so I'm leaving this one alone.  

Changing his strikeouts to 50 and keeping everything else equal, that's 543 batted balls  (650 PA - 57 walks - 50 strikeouts).  At his current pace of 39.2% fly ball ratio, that's 213 fly balls.   At 17.0% HR/FB ratio, that drops down to 36 home runs.  

What about his 39.2% fly ball ratio?  Over his prior 3 years it is at 36.6% and his career mark is at 36.2%.  While it's not glaringly higher, let's regress it to 36% anyway.  543 * 36% FB%= 195 fly balls * 17.0% HR/FB = 33 home runs.  

Now the big regression of his HR/FB rate.  Over his prior 3 years, it's at 8.4% and his career is at 10.2%.  He spent his 2010 season with the Red Sox and while playing half his games in Fenway, it was at 10.7%.  Over his last 2 years with the Tigers it was at 7.3% and 7.2%.  Let's say he only accomplishes 7.5% HR/FB the rest of the season.  He's currently at 47 fly balls, so 195-47 = 148 * 7.5% HR/FB = 11 more home runs this year, or 19 total.  

Victor Martinez has had a 2.6% home run rate over his prior 3 years, close to his 2.7% career mark.  Over his last 2 years with the Tigers it's at 2.0% and 2.1%.  Given 650 PA on the year or 512 more for this year: at 2.6% HR%, that's 13 more (21 total) and at 2.1% HR%, that's 11 more (19 total).  

In my 2014 preseason prediction for Victor Martinez, I gave him 13 home runs.  If I were redoing them, I would up it to an optimistic 20.  V-Mart is enjoying a bit of a power surge right now, but it's very likely unsustainable.

What Happens When Rick Porcello Is Not Getting Ground Balls

When Rick Porcello gets ground balls, he prevents runs.  Just look at this table, sorted by highest ground ball rate (using FanGraph's numbers):

Year	GB%	ERA
2013	55.3%	4.32
2009	54.2%	3.96
2012	53.2%	4.59
2011	51.4%	4.75
2010	50.3%	4.92
2014	43.9%	3.49

It's almost a perfect correlation that the higher Porcello's ground ball rate, the lower his ERA.  In fact, take out his rookie season and his current season and it is a perfect correlation.  The chart below shows Porcello's first 5 seasons in MLB and the trend line:

So when Porcello is showing his lowest ERA along with his lowest ground ball rate in 2014, it raises a red flag, even if it is only in 6 starts.  Using the formula of y = -0.0451x + 0.7321, with a GB% of 43.9%, we would expect an ERA of 6.50.  With an ERA of 3.49, we would expect a GB% of 57.5%.  Did he change his approach?  Is he just getting lucky?  Is it just a 6 game anomaly?

Rick Porcello has an 18.2% strikeout rate, a 4.1% walk rate and a 2.0% home run rate which results in a 3.16 FIP, the lowest mark in his career.  FIP uses strikeouts, walks and home runs and shows what a pitcher's ERA should look like.  

However, he has a 29.8% line drive rate and a 26.3% fly ball rate to go along with his 43.9% ground ball rate, which results in a 4.83 tERA.  tERA is another ERA predictor, but uses batted ball information.  SIERA kinda uses a combination of both FIP and tERA and says Porcello's ERA should be 3.50 (which is the closest to his actual 3.49 ERA).  His ERA estimators are giving off mixed signals.   

The 29.8% line drive rate is the highest of his career:

Year	LD%	GB%	FB%
2009	17.1%	54.2%	28.7%
2010	17.6%	50.3%	32.1%
2011	19.0%	51.4%	29.6%
2012	24.2%	53.2%	22.6%
2013	21.1%	55.3%	23.7%
2014	29.8%	43.9%	26.3%

Conveniently, Baseball Reference gives the exact same batted ball figures (FanGraphs and Baseball Reference use different sources for their batted ball data and usually they disagree on few batted ball types).  I have to switch to Baseball Reference here since FanGraphs doesn't go as deep into batted ball data for pitchers as they do for hitters.  According to B-Ref, Porcello has a .559 BAA on line drives in 2014.  For his career, his BAA on line dives is at .696 and typically it's around .700.  Simply put, Porcello is very fortunate that more of his line drives haven't fallen in for base hits and it's keeping his ERA low.    

Going to Brooks Baseball, we can see exactly what pitch is causing Porcello's lack of ground balls:



Porcello's ground balls on 4-seam fastballs are usually in the mid-40% range, but it has dipped all the way down to only 5.9% so far in 2014.  Conversely, his fly ball rate on 4-seam fastballs has gone up:


Porcello's lack of ground balls, high line drive rate and crazy 4-seam fastball trend hasn't hurt him yet, but it's something to keep an eye on in his next start and going forward.  I don't believe Porcello can continue to have success with this combination.