CHICAGO -- The Orioles always knew Jake Arrieta had this kind of potential, watching the right-hander -- drafted by Baltimore in the fifth round in 2007 -- go through some dominant stretches during an inconsistent 3 1/2-year O's career.
On Friday, Baltimore got a front-row seat to see Arrieta's development, as he continued to put together a career season with seven dominant innings for the Cubs against his former club. Arrieta, who retired the first 13 batters he faced, held the O's to one run -- Nelson Cruz's career-high 34th homer -- and outpitched O's righty Kevin Gausman to hand first-place Baltimore a 4-1 series-opening loss.
"I think he looked more mature," Cruz said of Arrieta, who he never played with him, but faced him several times as a member of the Rangers. "He was commanding all his pitches and he didn't make many mistakes."
Arrieta's gem halted the O's four-game win streak and drops their American League East lead to 8 1/2 games with Toronto and New York yet to play. The defeat was in front of a crowd of 33,761 at Wrigley Field, with plenty of orange and black on hand to see the club's first trip to the North Side of Chicago since 2008. And watch a very familiar Cubs starter.
"Those years were and still are very important to me for a lot of reasons," Arrieta said of his time in Baltimore prior to last July's trade. "Regardless of how certain situations went negatively or positively, they all impacted my career in a certain way. I'm thankful for those times over there, those years there, and I'll continue to use them for future reference, to reach back in the memory bank and think about certain times and certain situations that I had there, that I have now, and how I react and handle those. I think about it a lot."
Arrieta picked up his seventh victory of the season and improved to 3-1 with a 1.86 ERA in nine starts at Wrigley.
"He had it for periods for us," Showalter said of Arrieta's newfound consistency. "He was starting Opening Day [in 2012]. We knew. He's in a good spot, and we got quality in return [in trading him]. That's the way things work out. We wish him well. [We] wish we would have had some of those balls fall in today, we might have had a different story."
Instead, the O's got all their offense from Cruz. The Major League leader in homers, Cruz drilled Arrieta's 1-0 changeup into left field one out into the seventh inning. Arrieta allowed a two-out single to J.J. Hardy to prompt a mound meeting, but he stayed in and retired Jonathan Schoop to put the finishing touches on a quality outing.
"The changeup that Cruz hit wasn't really that bad of a pitch," Arrieta said. "He's just a big strong guy leading the league in home runs, and he's going to run into pitches like that. The pitch count was elevated because of not being able to go to a certain pitch early in counts to get an out."
The Orioles also watched a potential fifth-inning rally go by the wayside, as a crew-chief review confirmed the on-field ruling that catcher John Baker wasn't illegally blocking home plate on the inning-ending out.
Arrieta, who needed 48 pitches for the first four innings, allowed his first baserunner with Chris Davis' one-out single into center field. He walked Hardy, and one out later, Caleb Joseph singled into right field. A hustling Davis rounded third and headed home, with right fielder Ryan Sweeney's throw on target for Baker to apply the tag.
"If that's not blocking the plate, what is?," Showalter said after the call was confirmed in a 55-second review. "I'm totally confused now."
Gausman, who had a career-high seven strikeouts, fell uncharacteristically victim to the long ball. The 23-year-old allowed his first multihomer game of the season, surrendering solo shots to Luis Valbuena and Javier Baez over his five innings.
"I was a little sporadic today," Gausman said. "I thought I had pretty good command. I was able to go in on guys, get off the plate when I needed do. I just wasn't that good at minimizing. …Two swings are what really kind of hurt me."
Gausman, who was tagged with three runs, allowed three of his six hits in the Cubs' two-run fourth, and he exited after five innings in favor of pinch-hitter Cord Phelps. Chicago native T.J. McFarland was charged with a run in the sixth.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Facebook and Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.