SCOTTSDALE, Ariz. — After countless hours changing and honing his swing, the breakthrough at the plate finally came for Mac Williamson. The breakdown came elsewhere. 

What should have been the best year of Williamson’s career was wrecked by a collision with a wall at Oracle Park, and it was out on defense that Williamson finally realized his 2018 season needed to come to an end. Williamson never felt right after stumbling over a bullpen mound and going down hard on April 24, and when he started costing longtime teammates runs because he couldn’t track fly balls, the decision was made to shut it down.

The end came in August, with Triple-A Sacramento playing a road series in Nashville. 

“I was miserable,” Williamson said this week. “I couldn’t see the ball coming off the bat.”

There are ways for hitters to rationalize a slump. Perhaps your timing is off. Maybe one of the many moving parts in your swing is out of sync. But it’s much harder to make sense of things when you simply can’t track a fly ball, something you’ve been doing your whole life. That’s where Williamson’s ongoing concussion symptoms became most glaring. 

“When I started costing some guys runs, it was just like, I’m trying to push through this but it’s not just detrimental to me, it’s detrimental to other guys,” he said. “There aren’t a lot of variables out there on defense. Balls were getting hit to me and I was just sprinting in and all of a sudden they were one-hopping the wall.”

Williamson’s numbers, so eye-opening in April, had gone in the tank, too. On August 7, he made a return trip to Pittsburgh to see Dr. Micky Collins, a renowned concussion expert. 

“He was like, ‘You’re concussed,’” Williamson said. 

That didn’t come as a shock, especially not to Williamson’s girlfriend, Kaitlyn, who later would publish a heartfelt post describing a harrowing summer. She knew from the beginning that something was still wrong. Kaitlyn described her boyfriend sleeping 12-14 hours per day. He sometimes felt nauseous when he sat up straight. 

“He just was not himself,” she wrote. “There were times when I was just like, is this going to be the new Mac?”

The old version has returned this spring. 

Williamson was cleared of all symptoms in September, and as he did last January, he spent time in Los Angeles working with hitting instructor Doug Latta, who helped overhaul his swing last offseason and seemingly put him on the fast track to an everyday job. With the new swing, Williamson hit four homers last spring and posted an OPS over 1.000. That was just the beginning. 

The Giants did not break camp with Williamson in their immediate plans, but had no choice but to insert him in their lineup when he hit .487 with six homers in his first 11 Triple-A games. The first five games back in the big leagues brought three more homers. Williamson had arrived, and then a bullpen mound shook up much more than his season. 

Looking back, Williamson knows he was never close to his old self during the rest of the summer. He returned to the big league lineup after a month on the DL, but five days before he was called up to face the Cubs, he felt so sick that he had to stay at the hotel while the River Cats played a day game in Salt Lake City. 

“I felt like I had a severe, severe hangover. I couldn’t really get out of bed, I was super nauseous and I ended up sleeping the first couple of hours of the game,” he said. “A few days later, I was in Chicago.”

Major League Baseball has come a long way in dealing with concussions in recent years, but there is still no way to account for the pressure players feel during the course of a season. Williamson had waited his whole professional life for an opportunity like the one he was given in late April, and he was eager to pick up where he left off. He felt incremental improvement as he did rehab on his vestibular system.

“I felt like I would get over the crest,” he said. “It never happened.”

Williamson made several visits to Dr. Collins over the course of the summer and early fall. During one consultation, he was told something that sums up why it can often be so hard for big leaguers to fully get past concussions. So many of them return to the field, only to sit back down a week or two later. The Giants have dealt with this repeatedly, including with Brandon Belt, Joe Panik and Hector Sanchez. 

“The more stress you’re under, the more it plays up a lot of the symptoms,” Dr. Collins told Williamson. 

Playing in front of 40,000 fans is stressful under any circumstances. Doing it when you're trying to finally cement your spot in the big leagues only adds on. 

“They’ve given me a lot of opportunities in the past and I said last spring that this is kind of the last huge opportunity I felt I might be given, and I wanted to take advantage of it,” Williamson said. “I felt like I did, and then when I got hurt, we all wanted me to get back on the field as quickly as possible because I had been playing well.

"I wanted to get back out there. I missed it and I wanted to keep going, and we were winning. We started winning and it was fun.”

The good news for Williamson is that 2018 was not the last huge opportunity. If anything, the road is far less obstructed a year later. The Giants have no firm commitments in the outfield corners, and as Farhan Zaidi has said over and over again when asked about his young mix, Williamson is out of options. 

The overall numbers in 2018 weren’t good, the result of 52 post-concussion at-bats in the big leagues that Williamson shouldn't have been taking. But Bruce Bochy has not forgotten what he saw before the crash into the wall. 

“With what happened last year, I think you have to view him a litter different and realize, hey, we’ve always thought he had potential, but he showed it,” Bochy said. “That’s the difference now. This will be a big spring for him.” 

The Giants added Gerardo Parra and Cameron Maybin last week, but Bryce Harper isn’t here, and there are two open starting jobs. Williamson lights up when talking about the competition, pointing out that Steven Duggar is ready to shine, and Chris Shaw and Austin Slater have also tweaked their swings. He has seen a little bit of Drew Ferguson and expects him to be a factor. 

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But this lineup needs power, and Williamson proved last year that he can provide it. The staff will give him every opportunity to win a job this spring, and after a year of frustration, confusion and far too much nausea, Williamson is eager to grab it.

“From my standpoint, I feel like I’m going to go out there and kick ass and earn a spot like I did last year,” he said. “That’s what you’ve got to do. If you don’t have confidence in yourself, who’s going to believe in you? That’s how I’m looking at it.”