Velocity is a key component of grading out a pitching prospect’s fastball.

In 2019, the average four-seam fastball velocity topped 93.4 mph, nearly 1 mph faster than five years ago. Bullpens now almost exclusively feature arms that throw harder than 95 mph. All but two of the Top 10 starting pitchers based on Fangraphs WAR calculation had average fastball velocities above 94 mph. 

Fastball velocity is the first thing that jumps out when watching a start by the Cubs’ top pitching prospect Brailyn Márquez. The 21-year-old left-hander sits between 93-97 mph and touches 99 mph, as reported by Fangraphs (Baseball Prospectus has Márquez topping out at 100 mph).

On Fangraphs’ list of the top 88 left-handed pitching prospects in baseball, only five pitchers have topped out at 99 mph or greater. One of those five arms is Márquez, the youngest on the list by nearly two years.

Márquez throws from a side-arm slot as opposed to a traditional three-quarters delivery, meaning his release point is closer to the ground than a pitcher with a traditional three-quarters slot. His pitch mix consists of his hard fastball, a wipeout slider and a developing changeup primarily used against right-handed bats. Hitters are tasked with facing a pitcher who throws much harder than average, from a release point they don’t often see and from a handedness of pitcher that doesn’t often produce 99-mph flamethrowers.

Márquez threw 103.2 innings last season between Class A South Bend and High-A Myrtle Beach. His ERA was a respectable 3.13 with a stellar 11.1 strikeouts per 9 innings. Left-handed hitters had a particularly hard time against the lefty, slashing only .132/.266/.176 in 110 plate appearances. Right-handed hitters fared better but still struggled to generate extra-base hits (.385 SLG). 

The Cubs signed Márquez in August 2015 out of the Dominican Republic as a 16-year-old. He spent his first two seasons in professional baseball between the Dominican Summer League and the rookie-level Arizona League.

In 2018, he earned a late-season promotion from the Class-A short-season Eugene Emeralds to the Class-A South Bend Cubs. His major leap onto prospect radars came this past season when his performance in full-season ball started to catch up to the raw talent he possesses. 

In 2020, Márquez figures to see more innings with High-A Myrtle Beach after only 5 starts with the club at the end of 2019. A promotion to Double-A Tennessee during this season is within reach. Prospect sites like Fangraphs and Baseball Prospectus speculate Márquez could debut sometime late in 2021.

But for an arm this young, the Cubs have no need to rush his development. His success jumping from level to level will determine when he steps onto Wrigley Field’s mound for the first time.