SEATTLE -- Within the walls of the Mariners¡¯ clubhouse, many have already met ¡°Walter,¡± the imposing alter ego of Logan Gilbert. But on Tuesday night, the fiery and seemingly out-of-character second personality of the starting pitcher went mainstream.

On Gilbert's 101st and final pitch in a 3-0 win over the White Sox at T-Mobile Park, the towering right-hander blew a 98.6 mph fastball by AJ Pollock to strand two runners and cap his sixth scoreless inning. It was a tense sequence, with the tying run on third base and the go-ahead run on first.

Yet, Gilbert used every bit of his 7.5-foot extension down the mound, completely emptied the tank with his second-fastest pitch of the game, watched Pollock whiff and then clenched his fists and screamed with such raw emotion that brought to life the alter ego that¡¯s been heard of, but never quite seen.

Gilbert might have taken the mound ahead of that moment, but ¡°Walter¡± walked off.

¡°He is about as kindhearted, as nice -- I say a kid, but a young man -- as you're going to find,¡± Mariners manager Scott Servais said. ¡°He treats everybody with super all kinds of respect. But when it's his day to pitch and he steps out of the dugout to take the mound, it is on, and I love that about him.¡±

Even Gilbert's teammates who grew up alongside him in the Minors, including catcher Cal Raleigh, were wowed.

¡°The reaction was awesome,¡± Raleigh said. ¡°For him to come through in that moment is huge. And for him to gear back and be sitting 99 [mph] for those last couple batters was really impressive. That's like Justin Verlander stuff.¡±

Through pent-up frustration over shaky fastball command and the stakes of the moment, Gilbert -- or ¡°Walter¡± -- made the first of what could be many appearances as each passing game becomes increasingly important in Seattle's postseason push.

¡°I think it was a culmination of that -- close game, just a big moment and trying to make a big pitch,¡± Gilbert said. ¡°And then when I did, it just kind of came out. I don't even know what happened. I kind of just like blacked out.¡±

Despite the box score, dramatic finish and consecutive starts without allowing a run, Gilbert felt like he was ¡°off¡± on Tuesday. He threw first-pitch strikes to only 11 of the 24 White Sox batters he faced, had to labor back into counts and overcame what Servais called ¡°non-competitive pitches.¡± Yet, Gilbert's ability to navigate through the sixth without his best stuff underscored, in the Mariners¡¯ eyes, how far he¡¯s come.

Gilbert gave up five hits, walked none and struck out a career-high-tying nine, outdueling two-time All-Star Johnny Cueto, who stymied Seattle¡¯s bats and allowed only one run, which came on a throwing error by right fielder Gavin Sheets. Gilbert¡¯s resilience and mid-game adjustments are a huge reason why the Mariners are 18-10 when he pitches -- and why he¡¯d be such a valuable piece in the postseason.

Gilbert's four-seam fastball is his favorite pitch, but the refinement of his slider via a new grip has been huge. He induced whiffs on five of the 10 swings he generated on the breaking ball, four for strikeouts.

¡°I think as he gets more and more experience, you're only going to see more consistency with that -- because he likes to compete,¡± Servais said. ¡°He knows he's one of the better pitchers in the league.¡±

Since getting roughed up a bit by the Astros and Yankees twice apiece out of the All-Star break, Gilbert has hit a stride eerily similar to one last September. Over his past five starts (including Tuesday), he has a 2.15 ERA and has held hitters to a .239/.274/.303 slash line, with a 24.6-percent strikeout rate and 4.2-percent walk rate. Gilbert also hasn¡¯t allowed a homer during this stretch.

Gilbert and the Mariners received a big boost, after the righty left the game, from Raleigh, whose 23rd homer of the year came in the eighth and provided vital insurance, despite Seattle¡¯s collective shutout. Beyond Gilbert, Mariners pitchers have allowed three or fewer runs in nine straight games, the second-longest streak in franchise history behind only a 13-game run in 2014. Gilbert contributed to two of those, as he also tossed six scoreless innings in Detroit last Thursday.

That blowout victory didn¡¯t feature ¡°Walter"; the moment didn¡¯t call for it. But as the calendar gets deeper into September -- and potentially October -- the secret might be out on Gilbert¡¯s incredibly competitive alter ego.