Expected HR/FB Rates and Expected Home Runs

Home Runs per fly ball is widely known as a volatile number; in a small sample size it will not be an accurate indicator of a player’s power. The other constantly fluctuating statistics – strand rate and BABIP – have some scale that we can use to help approximate them. With a metric called xBABIP already created, I was wondering if I could find a tie in between HR/FB and something else. As I scanned my 2012 Baseball Forecaster, I knew immediately that I could use PX: Linear Weighted Power.

Linear Weighted Power (PX) is measured by this formula: ((Doubles*.8) + (Triples*.8) + (HR*1.4))/(AB-K) x 100. The league average PX is 100; the league average HR/FB is 10%. After seeing these numbers, I guessed that a 200 PX would give a 20% HR/FB. My research of the ratios confirmed this with impressive accuracy.

I scanned the entire player registry and found that it was not a perfect 10PX:1%HR/FB scale, but it was until I got to 140-150 PX. I came up with this scale: for a metric I will call xHR/FB.

90-110 PX = 10-11% HR/FB

115-125 PX = 12-13% HR/FB

125-135 PX= 14-15% HR/FB

136-158 PX= 15-16% HR/FB

160-170 PX = 17%-18% HR/FB

171-190 PX= 19%-20%

191-240 PX= 20%-25%

To illustrate the perceived volatility with HR/FB I will use Ryan Braun as a perfect example:

2007- 22% HR/FB, 2008- 17% HR/FB, 2009- 18% HR/FB, 2010- 14% HR/FB, 2011- 19% HR/FB, 2012- 21% HR/FB. A very random and volatile sample, it would appear. But is it?

  • 2007: 195 PX; 22% HR/FB
  • 2008: 167 PX; 17% HR/FB
  • 2009: 143 PX; 18% HR/FB (fairly lucky season but not by too much)
  • 2010: 133 PX; 14% HR/FB
  • 2011: 171 PX: 19% HR/FB
  • 2012: 196 PX: 21% HR/FB

While just one example, it’s pretty clear that PX and HR/FB will have a strong correlation in the long run.

Adam Dunn:

2007-2010 Dunn’s PX sat at 185-215; HR/FB sat between 21%-24%. In 2011, Dunn’s PX was 113 and HR/FB……..10%.

Andre Ethier

  • 2007: 108 PX, 9% HR/FB
  • 2008: 130 PX, 14% HR/FB
  • 2009: 148 PX, 15% HR/FB
  • 2010: 135 PX, 14% HR/FB
  • 2011: 97 PX, 9% HR/FB (injury mulligan can be given for his decline in 2011)

Now, using this new metric of xHR/FB, I wondered how I could use it to project home runs for players by year’s end. Max and Pace is a ridiculous waste of time; nobody cares that Josh Hamilton is on pace for 82 home runs, because that’s not going to happen. He cannot and will not sustain a 44% HR/FB ratio. However……………

His current PX sits at 266, which is aided by his HR/FB number. This improvement for Hamilton is real, but the HR/FB is not. Let’s assume Hamilton comes back to earth to the tune of a 210 PX- (Giancarlo Stanton and Mark Reynolds territory). We can then expect a still impressive 23% HR/FB (approximately).

I have created a new formula using my xHR/FB metric called xHR.

Formula: xHR= AB * CT% * Fly Ball% *  xHR/FB.

Here are some interesting names for this list of REAL Max and Pace data (all of these players’ on pace data for this season)!

NOTE: keep in mind this is providing the player keeps a contact and fly ball rate consistent with his current number for the rest of the year.

Josh Hamilton: 500 AB * .77 * .40 * .23 (substituting 44% HR/FB for his xHR/FB of 23%) = 35 Home Runs

Dare to dream? 600 AB gives: 43 HR

Ryan Braun: (2011 2H PX of 188, 2012 PX of 196) added to that is an increased fly ball total. xHR/FB of 21%; in 570 AB, Braun would hit 50 home runs.

Curtis Granderson: 2012 PX of 196, HR/FB of 31% not sustainable; expect to regress to 20%: 570 AB gives: 33 HR

Jay Bruce: 2012 PX is 210 and HR/FB is 20%. All systems go. 570 AB gives: 43 HR!!!!

Bryan Lahair: 2012 PX is 266 and HR/FB is 35%, both are completely unsustainable. Best case scenario: 200 PX (still high), 20% HR/FB in 500 AB gives: 22 HR.. 570 AB gives 28 HR. You can blame that atrocious 65% Contact rate

Andre Ethier: PX of 194 and HR/FB of 20%, no reason to think that’s unrealistic (some might disagree, given the bet at the bottom of this page) given his 170 PX in the second half of 2010. 570 AB gives: 35 HR

Those are all reasonable home run totals for those respective payers.

I will be making a full leaderboard at the end of May that I will post on the site! Until then, hope this has helped!

Follow Joshua on Twitter: @Rays_Nut1292 and please check out more of Joshua’s great work at AtHomePlate.com

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