DETROIT -- Matthew Boyd has arrived in Lakeland, Fla., for Spring Training the last few years with a major improvement over the previous season. He brought a re-tinkered slider and locked down a rotation spot in 2018. He focused on his fitness, revamped his training routine, continued to hone his slider and became the ace of Detroit’s pitching staff in '19.

When Grapefruit League play begins in a few weeks, expect Boyd to go to work on the rest of his pitches.

“At the end of every year, even throughout the year, you’re always looking: Where am I deficient? How can I get better,” Boyd said during the Tigers Winter Caravan. “Some of those things you can make adjustments in-season. Sometimes you can use the benefit of five months where you’re not pitching competitively. There’s little things I was able to do with my changeup and curveball that are a work in progress, that continue to come along, using the stuff we have available to make that better.”

Boyd didn’t consider himself a two-pitch pitcher last year. He didn’t forget how to throw the curveball and changeup that were more important parts of his arsenal when he first broke into the Major Leagues. But the more success he enjoyed early last season, the more he leaned on the fastball and slider, the two pitches that were the most effective for him early on.

Boyd’s slider was a wipeout pitch, good for a 43.4 percent whiff rate in 2019 according to Statcast. Opponents batted just .192 off of it in 2019.

His four-seam fastball, which dropped to an average velocity of 90.5 mph in 2018 according to Statcast, jumped to 92.1 mph in 2019 while gaining 102 rpm in spin rate, making it a legitimate swing-and-miss pitch for him. Correspondingly, the whiff rate on Boyd’s four-seamer jumped from 17.9 percent in 2018 to 24.1 percent last year, by far the highest of his career.

When hitters made contact with the fastball, however, it tended to be solid. The average exit velocity off the four-seamer jumped from 87.6 to 89.4 mph. Twenty-five of Boyd’s American League-leading 39 home runs allowed came against the four-seamer.

Considering it was the one pitch other than the slider that Boyd threw in abundance, hitters took advantage. Boyd’s fastball-slider combination was good enough to comprise more than 85 percent of his pitch selection, including 86.6 percent of his pitches in August, when he allowed 14 home runs.

By September, catcher Grayson Greiner was pushing Boyd to throw his changeup more, insistently signaling for the pitch. It comprised 20.8 percent of his pitches in 2017, but just 6.1 percent last year.

“I have four pitches that are all of good quality, and I need to use them. I can use them,” Boyd said last week. “What if I use them? Who knows if I can be a four-pitch pitcher as they continue to get better, what will happen? What will happen if I do use them? That’s a whole different realm that I handcuff myself in, in good and bad ways. With that, good things came about in how I was able to progress my game.”

Likewise, Boyd’s curveball has been a lesser-used pitch as his slider has become more prominent. Part of that involves how Boyd remade his slider, slowing it down from the mid-80s in his first few seasons to around 80 mph the last two years.

“It’s a give and take,” Boyd said. “It’s a balancing act and understanding what works for you and what doesn’t.”