SAN FRANCISCO -- A month into the season, the Padres' rotation has given its infielders quite the workout.
On the whole, Padres starting pitchers have combined for a 55.1 percent ground-ball rate this season -- a remarkable number that's nearly 11 percentage points higher than the league average. Of the six Padres to make at least two starts this season, five of them have induced grounders at a clip greater than 50 percent. Among them, only Jered Weaver does not fit the mold as a ground-ball pitcher.
"When they're good, they're all doing very similar things," Padres catcher Austin Hedges said of the Padres' sinkerballers. "When they're down in the zone, they're going to have success. When they're up in the zone, it's tougher."
Entering play Saturday, 151 pitchers had thrown at least 15 innings this season. Only eight had ground-ball rates above 60 percent -- and three of them were Padres.
Luis Perdomo (66 percent), Clayton Richard (65) and Trevor Cahill (61) all rank among the game's best in inducing grounders. Jarred Cosart (54) and Jhoulys Chacin (51) certainly qualify as ground-ball pitchers as well.

Through the years, pitching coach Darren Balsley has developed a reputation for accentuating his pitchers' strengths. That's on full display this year with a staff full of pitchers who work down in the zone.
"Bals' success isn't restricted to sinkerballers," said Richard. "It's more coincidental that he has a lot of us. But he's able to see what would be successful in a pitcher and ask them to do it more consistently. For our group of guys, that's a lot of sinkers. He's able to convey the mental aspect of, as sinkerballers, how to keep the ball down consistently and how to have your offspeed really play off that."
The San Diego bullpen hasn't been on the ground as frequently as the rotation -- at just a 41 percent clip. But there's an added value to starters who can induce ground balls, because they tend to get quicker outs and work deeper into games.
Since FanGraphs began tracking ground-ball rate in 2002, the '15 Dodgers rotation owns the highest single-season ground-ball rate, at 53.6 percent. There's a long way to go in the season, but Padres starting pitchers are on pace to beat that mark.
"It keeps guys into the game, and usually we play crisper games," said Padres manager Andy Green. "By and large, our infield defense has been pretty solid this season. ... It keeps everybody involved, everybody moving."
Of course, grouping all five of the Padres' sinkerballers as the same pitcher isn't fair. Their arm angles are very different. Their sinker usage rates are very different. And their complementary secondary pitches are all very different.
"Clayton's got the idiosyncratic movement with his hitch in his arm and the ball diving," Green said. "Perdomo is a traditional power sinker guy, coming at you low-to-mid-90s with sink. Chacin mixes it in. ... Cahill has the sinker, but the power curveball, too. They're all definitely different. To say they're all flatly sinkerballers is not painting the whole picture. Chacin is a radically different at-bat than Perdomo is."