He could be the last significant addition to the Phillies, who are content with slight changes to a roster that won 73 games a season ago.
It is rare to hear Amaro invoke the word "analytics" when discussing an acquisition, something he did with Hernandez.
"He had a lot of home runs," Amaro said. "He gave up a lot of homers last year and we think that's atypical with what he does. 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 was the highest for any pitcher with at least 150 innings since 2002, when Baseball Info Solutions began tracking batted-ball data. The Phillies are banking on his home run rate to regress, which is logical.
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 will aid Hernandez. Pitching in Citizens Bank Park may not.
Either way, his addition is not the panacea to the Phillies' many problems. The Phillies are at or near their budgeted payroll. Amaro said he wished to spend his money "wisely and intelligently."
Thus, he will rely upon some combination of Hernandez, Kyle Kendrick, Jonathan Pettibone and Miguel Gonzalez to occupy three rotation spots. Kendrick, who pitched to a 4.70 ERA last season, slots as the third starter behind Cole Hamels and Cliff Lee.
"I don't know if he's a 'three' starter," Amaro said. "I know he's pretty reliable, pretty consistent. He has over 60 wins over the last several years. For a guy that I guess takes a lot of heat, he still wins baseball games. We need people to eat up innings and be reliable and he's been one of those guys for us."
Former catching prospect Sebastian Valle was designated for assignment to clear space for Hernandez. Valle, 23, once ranked as high as third on Baseball America's rankings of Phillies prospects. He fell down the depth chart after two dismal seasons, although two scouts believe a team will claim Valle off waivers.