SEATTLE -- After striking out eight times through four innings, the White Sox looked as if they might go quietly against the Mariners on Sunday at T-Mobile Park. But Chicago’s eight-run fifth inning offered a reminder for how much weight its lineup could carry into 2020, though its pitching staff’s 11 walks also showed why that remains its the club's most glaring defect.

Jose Ruiz loaded the bases in the bottom of the ninth, then issued a walk-off walk to Mariners catcher Tom Murphy that left Chicago with an 11-10 loss.

• Box score

The walk-off defeat was Chicago’s second in as many days after Alex Colome gave up a solo homer to former White Sox catcher Omar Narvaez in the 10th inning on Saturday.

Sunday’s outcome spoiled what was shaping up to be an impressive comeback. Welington Castillo hit a go-ahead grand slam as the White Sox batted around in the fifth to help erase the five-run deficit that Ivan Nova created after just 3 1/3 innings.

But Kelvin Herrera helped the Mariners come back by serving up a three-run homer to red-hot Mariners rookie Kyle Lewis, then Josh Osich allowed an RBI single to Mallex Smith that tied the game at 10 in the eighth.

Here are three takeaways from Sunday’s game.

1) The pitching staff is struggling to stay in the zone

The White Sox threw 201 pitches Sunday, 77 of which were called balls. That ballooned their season walk total to 548, for a rate of 9.6 percent -- both of which rank third worst in the Majors. Even while operating with a tight strike zone from home-plate umpire Alex Tosi, the club acknowledged that far too many pitches were bleeding away from the plate.

“A lot of walks today. A lot of leadoff walks,” White Sox manager Rick Renteria said. “Those are things that we have to certainly clean up, in general. You see what happens on a Major League field and it's not easy to win a ballgame on a daily basis, no matter who you're playing.”

Nova only issued one free pass, but he also gave up 10 hits before being pulled for Hector Santiago, who walked six. Santiago was scoreless for 3 2/3 innings, allowing the White Sox to crawl back. But he allowed each of his first three batters in the eighth to reach, and they all scored, including two on Lewis’ homer.

2) There’s a lot to like about the offense

Yoán Moncada and Eloy Jiménez had three hits apiece, as they both flashed their best attributes at the plate. Moncada hit two singles with an exit velocity of 95 mph or higher (the threshold that Statcast classifies as hard-hit) and he stole his 10th base. Jimenez’s two hits that reached the outfield were both center-to-opposite field, which is reflective of his approach that the White Sox rave about.

Two of Moncada’s hits came against Justus Sheffield, elevating his batting average against lefties to .284, up from his .209 average in 2018, and he also singled against righty Austin Adams. As a left-handed hitter, Moncada leads all qualified batters with a 93.6 mph average exit velocity.

Castillo drove in a season-high five runs in what’s been a challenging season. His .652 OPS entering Sunday was on pace for a career worst in seasons he’d accumulated at least 100 plate appearances. And Adam Engel hit three-run shot a Statcast-projected 415 feet into the second deck in left to help spark the fifth-inning rally.

“We thought we put ourselves in a good position, continue to tack on runs, got five runs ahead,” Renteria said. “We tried to get some of these guys to go ahead and finish off the ballgame.”

3) Collins continues to develop behind the plate

Zack Collins was behind the dish for all nine innings of the three-hour, 44-minute contest and was charged with guiding the club’s pitching staff back into the zone. Collins’ catching duties have been relegated mostly to the No. 5 rotation spot -- a challenging task for any catcher, but particularly a September callup who entered Sunday with a .113/.254/.226 slash line at the plate.

“Obviously, there's an adjustment,” Collins said of guiding the seven White Sox pitchers Sunday. “You obviously don't want to throw it down the middle. Then they hit homers and they hit doubles and stuff like that happens. We still try to work the corners, but maybe thirds of the plate and stuff like that. I mean, sometimes, the calls that kind of change at-bats, we didn't get them today.”

Collins also went 1-for-4 at the plate with two strikeouts.