CHICAGO -- The month of May is winding down and that must bring a twinge of sadness to Ben Zobrist. The Chicago Cubs' veteran second baseman is in the midst of a career month and is likely to unseat Dave Winfield for the title of "Mr. May."

Of course, the difference is there would be nothing derisive about the nickname in this case.

Zobrist entered Sunday ranked among the National League leaders in batting average (.429, second), on-base percentage (.505, first), on-base plus slugging (1.175, third), runs (23, first), and runs batted in (22, first) during May. Incredibly, he batted .474 in the previous 21 games to raise his batting average from .250 to .354.

Ben Zobrist's three-run home run helped the Cubs break open a tight game against the Phillies on Sunday. Matt Marton/USA TODAY Sports

He managed only one hit in four at-bats Sunday but made it count by blasting a two-out, three-run home run in the third inning to break open a tight game and power the Cubs to a 7-2 win over the Philadelphia Phillies, which extended Chicago's winning streak to five games.

Despite his "off" day, Zobrist -- who has never batted .300 in 10 previous seasons -- is second in the major leagues with a .351 average and leads baseball with an on-base percentage of .451.

What gives? Players his age (he turned 35 on May 26) usually are on the decline, not in the midst of the best stretch of their careers.

"I'm trying to figure out myself if I can keep this up, to be honest," Zobrist said. "I don't think I've ever had a month where I've hit this well and just kind of all the way around. You just try and keep it going. That's all I'm trying to do -- doing the same things, the same drills, trying to manage my body well and have good at-bats.

"I didn't have great at-bats today outside of the ball I hit out. It's just a daily grind. You just keep working and try to have quality at-bats."

Before the game, manager Joe Maddon said Zobrist was the biggest surprise of the season so far.

"I mean, I expected him to play well," Maddon said, "but he's exceeding that expectation level a little bit right now."

In fact, Zobrist is hitting so well he has created an issue for Maddon. The manager knows he must periodically rest a 35-year-old, but how can you sit a player when he's this hot?

Zobrist was asked if he would tell Maddon not to rest him right now.

"No, I'm not saying that," he said. "We've already talked about not playing every day this week because we've got about a 13-game stretch. The end of the last nine-game [stretch] before we had an off day, I was starting to feel it a little bit.

"I can tell there are times when my body's getting tired and I just need to take a day here or there and make sure I'm healthy."

Zobrist said he was trying to not think too much about what is causing his hot streak.

"I can tell I can't do the same things I did five, six, seven years ago, but it's still good enough to where I'm able to get the barrel to the front of the zone when I need to," he said. "That's the thing: when you're going well, 97 doesn't seem hard, and when you're not going well, 87 seems really hard. I'm just seeing the ball well and I'm on time and it's just been a great stretch for me.

"Sometimes hitting feels like you're holding napkins down in the wind. 'I've got to do this and this and this' -- and then you have the ball coming at you. But lately, I haven't even had to do that. That's the crazy thing about it. After I do my pregame work, I feel pretty locked and I can focus on the ball coming at me and what the pitcher's trying to do."

With the win, the Cubs improved to 34-14 and reached one of their stated milestones: getting 20 games over .500.

"It goes back to the good start," Maddon said. "We talked about that in camp, that it was so important to get off to a good start. We just absorbed a little bit of a hiccup and now we're 20 games over, whereas a week ago we were talking about stubbing our toe a little bit. That's what a good start allows you to do.

"It's not lost on me. I was aware we could be 20 over after today, and now the next goal is 25, obviously."