BOSTON — Speaking about the knuckleball, longtime catcher and broadcaster Tim McCarver once said: “Hitting that thing is like trying to catch a butterfly with tweezers.”

Slugger Nolan Arenado, who has never faced a knuckleballer before, gets his chance to chase the butterfly Wednesday night when the Rockies face Boston right-hander Steven Wright at Fenway Park. Arenado has watched video, but he’s not sure what good that will do. He also contacted some people who have faced Wright, including former teammate Troy Tulowitzki, who now plays for Toronto in the American League East.

“I’m not sure what to do,” said Arenado, who entered Tuesday night’s game hitting .294 with 14 home runs, tied for second-most in the majors. “I’ve texted Tulo, and he’s giving me a little bit, here and there. But it will be different, it will be a little weird.”

Wright was traded to the Red Sox in 2012 and nearly retired the following winter before finally making his major-league debut in 2013 at age 28. He bounced between Triple-A and the majors for three seasons before claiming a spot in Boston’s starting rotation out of spring training. Wright entered Tuesday ranked sixth in the American League with a 2.52 ERA.

“(Boston’s) Tim Wakefield was the last knuckleballer I faced,” right fielder Carlos Gonzalez said. “So it’s tough. I think a lot of it is about instincts up there. I mean, what are you going to think about? It can be different every night. You just have to go up there and react and try to get one around the strike zone.”

Motte’s debut. Right-handed reliever Jason Motte signed a two-year, $10 million deal in early December but has yet to make his Rockies debut because of an injured shoulder. It will come Wednesday or Thursday against the Red Sox. He pitched back-to-back games for Triple-A Albuquerque, so he wasn’t available Tuesday.

Motte, who turns 34 next month, said his shoulder feels “great.”

“It took some time, but you can’t rush a shoulder,” said Motte, who strained his shoulder during spring training and spent nearly two month rehabbing it. “If you do, you will end up worse than where you started. You have to trust the process and take baby steps.”

Motte was competing with Jake McGee for the closer’s role in spring training before he got hurt. He eventually could be used in the eighth inning, but manager Walt Weiss won’t rush Motte into pressure situations.

“I’m probably not going to put him in during the eighth inning of a one-run game. … I’ll try to ease him in,” Weiss said. “At some point I see him pitching late in games.”

Footnotes. Right-handed batter Ryan Raburn was the designated hitter Tuesday night and likely will continue that role throughout the three-game series. … Pittsburgh pitcher Ryan Vogelsong, hit in the face by a 91 mph fastball by Rockies right-hander Jordan Lyles in Monday’s game, was placed on the 15-day disabled list with facial fractures, the Pirates announced Tuesday. Vogelsong left PNC Park in an ambulance and was admitted to Allegheny General Hospital. The team said after Monday’s game that he had suffered an injury to his left eye, including the orbital bone.

Looking Ahead

Rockies RHP Chad Bettis (4-2, 4.18 ERA) at Red Sox RHP Steven Wright (3-4, 2.52), 5:10 p.m. Wednesday, ROOT, 850 AM

Bettis, along with fellow right-hander Tyler Chatwood, has been a workhorse for Colorado. He has pitched at least six innings in eight of his nine starts. Bettis is 3-1 with a 4.25 ERA in six road starts. He has faced Boston just once, pitching an inning of relief in September 2013 at Coors Field. Wright, a “hard-throwing” knuckleballer, kept Kansas City off-balance in his last start, getting charged with just five hits in a complete game. However, a two-run homer by Eric Hosmer and a sacrifice fly by Alcides Escobar beat Wright and the Red Sox 3-2 in the opener of a split-doubleheader.

Thursday: Rockies RHP Jon Gray (1-2, 6.75 ERA) at Red Sox RHP Clay Buchholz (2-4, 5.92), 5:10 p.m., ROOT

Friday: Giants RHP Matt Cain (1-5, 5.37) at Rockies RHP Eddie Butler (2-2, 3.96), 6:40 p.m., ROOT

Saturday: Giants LHP Madison Bumgarner (6-2, 2.17) at Rockies RHP Tyler Chatwood (5-3, 3.02), 2:10 p.m., ROOT