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Phillies, using advance metrics, bet on Roberto Hernandez

Desperate for another starter, Ruben Amaro Jr. sought an undervalued commodity. He cited advanced metrics as a reason for signing Roberto Hernandez.

The Phillies were never in the market for a mid-level starting pitcher, let alone a frontline one. The prices for pitching would stretch the Phillies beyond their self-imposed $170 million payroll limit. So, desperate for another starter, Ruben Amaro Jr. sought an undervalued commodity.

"We think Roberto Hernandez will help us," Amaro said. "Our scouts and our analytics people looked at the middle-of-the-road, back-end starters and we felt like he would be a good choice for us."

Hernandez's $4.5 million deal was made official Wednesday when he passed a physical in Philadelphia. The contract includes an additional $1.5 million in performance bonuses based on innings pitched. The former Fausto Carmona was not made available to reporters.

It is rare to hear Amaro invoke the word "analytics" when discussing an acquisition.

"He gave up a lot of homers last year and we think that's atypical with what he does," Amaro said. "He's more of a ground-ball guy. We think that he's going to be better than that, particularly."

Simply put: The Phillies think Hernandez will be luckier in 2014.

He allowed 24 home runs on 115 fly balls, which equated to a 20.5 percent rate, according to FanGraphs. That was, by far, the highest home-run-to-fly-ball rate for pitchers with at least 150 innings in 2013. The next closest was Houston's Dallas Keuchel at 17.4 percent. The major-league average was 10.5 percent.

In fact, Hernandez's 20.5 percent rate is the highest for any pitcher with at least 150 innings since 2002, when Baseball Info Solutions began tracking batted ball data.

So the Phillies are banking on that outlying rate to regress, which is logical.

Most pitchers (min. 150 innings) since 2002 with a HR/FB rate higher than 17 percent showed improvement in ERA during the following season. The average change was 0.72 runs lower the next season:

Hernandez's expected fielding independent pitching (xFIP) in 2013 was 3.60. That metric attempts to account for everything a pitcher can control — strikeouts, walks, hit batters and home runs — while normalizing the home-run rate. This metric assumes a pitcher has little control over balls put in play. It is viewed as a way to predict future results.

The traditional numbers do not favor Hernandez. He has a 5.03 ERA since 2008, which is the second-highest for any pitcher with at least 800 innings. (Kansas City's Luke Hochevar is worse with a 5.15 ERA.) Amaro believes changing leagues, and specifically not being in the American League East, will aid Hernandez.

Either way, his addition is not the panacea to the Phillies' many problems. Amaro will bet on a shaky rotation after Cole Hamels and Cliff Lee.

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