SAN FRANCISCO – Whiff rate? We're talking about whiff rate? Not a game, not the five starts in May that made Chicago wonder why it let Jake Arrieta walk away? We're talking about whiff rate. We're talking about whiff rate, man. How silly is that?

Just like Allen Iverson questioned the value of practice, Jake Arrieta is planting doubts about the need for swings and misses. And his performance – a 0.90 ERA in May despite a career-low strikeout rate – seems to be a solid argument.

Arrieta is striking out batters at his lowest rate since 2010 and is generating nearly 50 percent fewer whiffs than he did in 2015, when he won the Cy Young Award. His strikeout  rate — Arrieta registers swinging strikes on just 6.6 percent of his pitches — is the fifth lowest among all starters who have thrown at least 50 innings. Yet he has a 2.16 ERA after 10 starts.

"Everybody likes strikeouts, which is great. But outs are most important," said Arrieta, who will start the  series finale Sunday against the Giants. "It doesn't matter how they come."

Arrieta struck out 9.3 batters per nine innings in 2015 and had the sixth most strikeouts in the majors. The velocity of his sinker – Arrieta's go-to pitch – was nearly 2 mph  faster in 2015 than it is now. That dip in velocity coincided with a dip in strikeouts — Arrieta is striking out just 6.2 batters per nine this season. Fewer strikeouts means more contact, which, for Arrieta, actually means success.

Knowing he lacks the velocity to blow hitters away, Arrieta is simply going after hitters. His contact rate is 30 percent higher than it was when he won the Cy Young. He's throwing first-pitch strikes to 63.5 percent of his batters, the highest rate of his career. He is welcoming the challenge. And he's winning.

Arrieta has the highest ground ball rate in the majors, a mark that is 11 percent higher than last season's. He is trading strikeouts for weak contact. The increased contact rate sounds troubling. But those concerns can be quelled when a majority of that contact is harmless.

"I have seven guys behind me. I'm not going to pitch away from contact," Arrieta said. "I could strike more guys out if I threw more four-seams and threw more breaking stuff, but why do that if I could throw more efficient innings with less pitches? … I pitch to contact and get a punch-out when I need it. I'm trying to get 27 outs,  and if I can't do that, I'm trying to get as close as I can."

The weak contact off Arrieta comes from his sinker, which he is throwing more than in any season since his rookie year. The sinker's velocity — an average of 93.58 mph — is not at the level it was in 2015 but it is 1 mph faster than it was last season, when the Cubs thought Arrieta showed enough flaws that it was time to move on.

The pitcher has been revitalized. The sinker  has as much vertical movement as last season with a jump in horizontal movement. And nearly 60 percent of the sinkers that have been hit have been ground balls. Those flaws are no longer so glaring.

"Sink and deception. He's got a ton of both," manager Gabe Kapler said. "He steps across his body and he hides the baseball a little bit. He's got an interesting arm angle that creates a lot of sink and run. So he's off the barrel a lot. And when you're off the barrel a lot and the ball is moving down, inevitably guys hit the ball on the ground."

"Fly ball pitchers who give up their high velocity off the bat, they end up getting beat with home runs. Guys who have good sink and movement down like Jake, guys can square up the baseball, but it's going to be right into the ground. We have a chance to catch it and throw it out."

Arrieta struck out just six batters per nine innings in his five May starts. He averaged just 7.4 swing and misses per game. Yet he became just the seventh Phillies pitcher to make five starts in a month and register an ERA lower than 1.00. Arrieta proved in May that he can pitch without whiffs.

"I don't overthink things," Arrieta said. "I understand that if I put the ball in a general area with some decent movement, then they're not going to do much with it. That's kind of where the results come from. Doing it time and time again and you know that if you're able to execute and be able to put the ball in a general area where you're trying to, the results are going to be in your favor more often than not."