ARLINGTON -- The Rangers are making themselves felt all over the National League pennant races.

They tightened the NL West by defeating division leader Arizona, 5-3 at Globe Life Park on Monday night.

Robinson Chirinos drove in four runs, three on a homer off Diamondbacks ace Zack Greinke. Relievers Eddie Butler, Cory Gearrin and Jose Leclerc sealed Bartolo Colon's win with four scoreless innings.

The Chicago Cubs have begun to separate themselves in the NL Central by winning all three games started by recent acquisition Cole Hamels, the former Rangers left-hander. If the Cubs get into the playoffs as expected, Hamels could be their opening-game starter.

It is a remarkable transformation in a short time for Hamels, whom the Rangers traded to the Cubs on July 27 for Butler, minor league right-hander Rollie Lacy and a player to be named. The Rangers also ate enough of Hamels' contract to keep the Cubs under the luxury tax threshold.

Hamels was 5-9 with a 4.72 ERA in 20 starts with the Rangers. He gave up seven runs in three of his final four starts with the Rangers. Hamels allowed 48 extra-base hits, including 23 homers, in 1141/3 innings.

Hamels is 2-0 with a 1.00 ERA in three starts with the Cubs. He has not allowed an extra-base hit in 18 innings.

Are the Cubs' pitching minds that much smarter than the Rangers'? Did the Cubs see something the Rangers missed? Have the Cubs made massive changes with Hamels?

The answer to each question is NO.

Cubs manager Joe Maddon told reporters that he and pitching coach Jim Hickey made a point of not overloading Hamels with information and suggestions when he joined the club July 27. They let Hamels continue to do his own thing, because he knew himself better than anyone with the Cubs.

The Rangers believed Hamels was close, in the weeks leading up to the trade, to finally locking in the timing of his delivery. Pitching coach Doug Brocail and assistant Dan Warthen were convinced that together with Hamels, they had found the way to keep his body back in the delivery.

"In Cole's words, it would come and go," manager Jeff Banister said. "From what I know about Cole and the athlete that he is, the hard worker that he is, it was just a matter of time before he put it together. It's not surprising."

Hamels said as much in a postgame meeting with reporters after holding Washington to one run with one hit and nine strikeouts Sunday.

"I was really focusing a lot, even when I was down there [with the Rangers], trying to correct my mechanics," Hamels said. "That was something that was off, and I knew it was off. It was just a matter of trying to identify and then putting in the work to get the muscle memory so I could perform at the level I know I'm capable of doing.

"It's now being able to get the results. That's how you build momentum, how you get back to what I know I'm capable of doing."

Hamels acknowledged the trade invigorated him. He went from a club that was hopelessly out of contention at 25 games out to a club trying to win the World Series for the second time in three seasons.

"Anytime you get placed into a pennant race, you start to discover a little bit more that's in the tank that you might not necessarily have been able to go down and really gather," Hamels said.

Said Maddon: "He's probably been reborn a little coming to us."

Twitter: @gfraley