Making it doubly tough was the fact right-hander Jeff Weaver was in position to win his first game of the season, thanks to his own abrupt turnaround after another rocky first inning and left fielder Raul Ibanez's three-run double that capped the Mariners' four-run sixth inning.
But this was a lead that did not stand up and Seattle lost its second straight one-run game after beginning the four-city, 10-game road trip with five consecutive wins.
This was a tale of two pitchers.
Morrow and Weaver had adjoining lockers in the visiting clubhouse during the three-game series and as one of them explained what went right in the series finale, the other explained what went wrong.
"I have been getting myself in trouble with walks all season, and eventually it was going to get me," Morrow said. "That was today."
The Mariners' first-round draft choice in the 2006 First-Year Player Draft earned a spot in the bullpen during Spring Training, largely because he had such good command of the strike zone.
While he has done an excellent job as the right-handed setup man for closer J.J. Putz, reeling off 18 2/3 consecutive scoreless innings before surrendering one run to the Indians on Monday, Morrow's walks have steadily increased -- from seven in 10 1/3 innings in April, to 10 in 10 innings in May and nine free passes in 5 1/3 innings in June.
"I don't know why," he said. "I do know that I have to start throwing more strikes."
Catcher Jamie Burke said Morrow wasn't missing by a lot, and a couple of borderline pitches were called against the young right-hander. But he also put the inning in perspective.
"It was one of those days," he said. "Brandon has picked us up plenty of times this season, and everyone's going to have these days once in awhile."
There was no indication that the increase in free passes is diminishing manager Mike Hargrove's faith in the rookie right-hander.
"It's not the first time he has walked some people, but it's the first time it came back to bite him," Hargrove said. "He has the kind of stuff that he can do that and still pitch out of it. But he just didn't do it today. It was one of those things.
"We felt good about where we were in the ballgame and the guys we had coming in," he added. "It just didn't happen for us today."
On the flip side, Weaver continued to show improvement -- once he got past the first inning.
The Cubs came out swinging, scoring three runs in the first inning.
Alfonso Soriano greeted Weaver with a leadoff broken-bat double to left field, which ended an 0-for-21 slump, and he scored when Felix Pie tripled to right-center. After Derrek Lee popped out, Cliff Floyd singled to center field to make it 2-0 and Floyd scored on Mike Fontenot's two-out triple to right field.
The early barrage was the latest in a string of rough starts for Weaver. In the first inning alone this season, opposing hitters are 24-for-44 (.568) against him with seven doubles, three triples, one home run and 20 RBIs.
But whatever Weaver did between the first and second innings worked wonders.
"From the second inning on, he was lights-out," catcher Jamie Burke said. "I have caught him two previous times and his stuff today was as good as anybody's. Not to use it as an excuse, but like Wash [Jarrod Washburn] was saying the other night, the mound here is a little different than most. He said it seemed like he was throwing uphill."
"I have been here before and know there is a difference [in mounds]," Weaver said. "You just have to make sure your pitches are down. The mound is pretty flat and that causes you to be up in the zone, but I don't know if that had anything to do [with the first inning].
"The only thing I was really upset with in that first inning was the third run I gave up. I felt that if I had stayed with cutters inside on Fontenot, he might have hit a ground ball to first base, but I got a pitch up more than I wanted. Other than that, I was pleased with the execution of my pitches, and it's another step in the right direction."
Though he allowed at least one hit in each of the next five innings, Weaver held the Cubs scoreless, hoping his offense would find a way to score against right-hander Jason Marquis. It took awhile and the solution began when, with one out in the sixth, Weaver was hit by a pitch.
Ichiro Suzuki walked and Jose Lopez reached on an error by third baseman Mark DeRosa, who had a potential inning-ending double play skip through his legs, allowing Weaver to score. After Jose Guillen walked, loading the bases, Ibanez drilled a line drive into the gap in left-center, scoring all three runners.
The play ended with Guillen accidentally brushing against plate umpire Tim McClelland, who was standing on the first-base side of home plate. The ump took exception to the incidental bump and pointed his finger at the Mariners right fielder.
Hargrove and third-base coach Carlos Garcia finally had to settle down both parties.
"Jose was trying to avoid running over Tim," Hargrove said. "For whatever reason, [McClelland] thought Jose was mad at him. It was more Tim than anything else."
After the game, the Mariners optioned left-handed pitcher Jake Woods back to Triple-A Tacoma and are expected to activate left-hander Ryan Feierabend before Friday night's series opener against the Astros in Houston.