Dunn entered his junior season at Boston College in 2016 as an intriguing college closer. It was when he showed he could start as a junior that he shot up Draft boards and into the first round, where the Mets took him with the 19th overall pick. After two full seasons with the Mets, reaching Double-A in that second full year, he was sent to the Mariners in December 2018 in the Robinson Cano trade. A lot more clicked as he led the Texas League in strikeouts and WHIP, pitched in the Futures Game and made his big league debut in 2019.
Dunn has shown steady improvement since he entered pro ball, catching up quickly given his lack of previous starting experience. He’s relied heavily on his fastball and slider, both plus pitches at times. He’ll throw his fastball up to 95 mph and sat around 92-93 in 2019 and his slider has become a true out pitch, one he threw a lot in the big leagues and got swings and misses there. It’s consistently graded as a plus pitch both by scouts and on analytic scales. There is some feel for a changeup, and he threw it for more strikes than he had previously in 2019, but he’ll have to show more conviction in throwing it for life in the big leagues. He’ll still use his curveball, but it’s more of a show pitch to get strike one than anything else.
While it didn’t show during his brief time in the big leagues, Dunn did a better job of finding the strike zone in Double-A in 2019. He’ll have to keep refining his command, along with that changeup, to stick as a big league starter, something the Mariners have full confidence he’ll be able to do.
Scouting grades: Fastball: 60 | Slider: 55 | Curveball: 50 | Changeup: 45 | Control: 50 | Overall: 55
Dunn pitched out of Boston College's bullpen for most of his college career, but scouts got excited when he took his full repertoire to the rotation as a junior. That turned him into a first-round pick and the Mets nabbed him at No. 19 overall. After struggling a bit in his first full season, the right-hander went back to the Florida State League and pitched his way to Double-A in 2018. The Mariners noticed the rebound and acquired him as part of the package for Robinson Cano and Edwin Diaz in December.
There hasn't been any issue with Dunn's stuff since he entered pro ball. He'll sit in the 93-95 mph range with his fastball and can reach back for more at times. He does have a pair of breaking balls, with his slider ahead of the curve. He'll throw the harder slider with good late bite and it looked like a plus pitch for him at its best in 2018. Dunn is still working to develop his changeup, though he shows some feel for it. He's made progress in getting left-handed hitters out, using that third pitch more effectively at times.
While Dunn's overall command and control have been inconsistent in his brief career, the Mariners feel they saw a better strike-thrower as he got settled in during his bounce-back 2018 campaign. He is athletic, which should help him repeat his delivery. Staying healthy helped Dunn take a nice step toward his ceiling as a mid-rotation big league starter.
Scouting grades: Fastball: 60 | Slider: 55 | Curveball: 50 | Changeup: 45 | Control: 45 | Overall: 55
Dunn spent most of his time at Boston College as a reliever, albeit one with multiple pitches. A move to the rotation during his junior season greatly improved his Draft stock, landing him in the first round where the Mets nabbed him with the No. 19 pick in the 2016 Draft. After a solid summer debut, the Mets sent Dunn straight to the Class A Advanced Florida State League for his first full season and he struggled a bit there, finishing the final month of the season on the disabled list. He bounced back with a strong 2018 season, pitching his way to Double-A, and then he was dealt to the Mariners in the offseason blockbuster trade that sent Robinson Cano and Edwin Diaz to New York.
Even when he struggled, Dunn was just fine pure stuff-wise. His fastball was consistently in the 93-95 mph range and he was able to reach back for more on occasion. His slider can serve as a true out pitch, flashing plus with good late bite. As a reliever, he hadn't worked on his changeup much, and it's behind the other two pitches, but he does show feel for it. He'll need it to get lefties out, something he's made some progress with. Dunn is athletic and repeats his delivery fairly well, but he has had some command and control issues.
A certain learning curve was to be expected, given Dunn's lack of starting experience, though being shut down at the end of his first season didn't help quiet detractors who worried about his size and durability. He answered some of those questions with his strong 2018 campaign, showing he has the stuff, and stamina, to start.
Scouting grades: Fastball: 65 | Slider: 55 | Curveball: 50 | Changeup: 45 | Control: 50 | Overall: 50
While Dunn was dominating out of Boston College's bullpen during his junior season in 2016, scouts wondered what his full arsenal would look like as a starter. BC obliged, moving Dunn into the rotation mid-season. The right-hander's stock took off, and he landed at No. 19 overall in the first round before going on to throw very well in the New York-Penn League during his summer debut. His first full season in the Florida State League has not been as successful, however.
An athletic hurler, Dunn has a feel for four pitches thrown with a free and easy delivery. Over the summer, his fastball sat at 95 mph and he touched 98 mph at times. He throws both a slider and curve, with the former ahead of the latter currently, though the Mets feel both could eventually be at least above-average. Because of his history as a reliever, Dunn's development of his changeup lagged behind, but he does have some feel for it and just needs to throw it more. He tends to be around the strike zone and, with his athleticism, projects to have at least solid average command in the future.
Because of his size and lack of track record, there are some who wonder about his durability as a starter over the course of a long season. He'll get the chance to prove those doubters wrong during his first full season, with the stuff to pitch near the top of a rotation one day.
Scouting grades: Fastball: 60 | Slider: 50 | Curveball: 50 | Changeup: 45 | Control: 45 | Overall: 50
At the start of the spring, Dunn was an interesting college reliever with arm strength, albeit one with a four-pitch mix many scouts were intrigued to see as a starter. They got their wish as Dunn became a part of Boston College's weekend rotation in April and saw his Draft stock take off.
Dunn has always had a plus fastball and he maintained it in his early starts, lighting radar guns up to 98-99 mph and sitting in the 92-95 mph range. He utilizes two breaking balls, both of which are Major League average: a three-quarters curve and a solid hard slider. His changeup will also flash average, though he didn't need it much as a reliever. His command is fringy at present, but his outstanding stuff helps make up for it.
Many teams feel Dunn has a very good chance to start as a Yordano Ventura type athletic, yet slightly undersized, right-hander. As a result, he was flying up boards, with some feeling he could be gone by the end of the first round.