Glaring flaw could derail any hopes of this top Cubs prospect making an impact

As the Chicago Cubs look to help All-Star outfielder Pete Crow-Armstrong reset after his recent struggles, it's all eyes on Kevin Alcántara, who joined the team when rosters expanded on September 1, taking the place of Owen Caissie, who was optioned back to Triple-A Iowa in a corresponding move.

Make no mistake: this isn't a benching of or a moving on from Crow-Armstrong. The Cubs know they need their dynamic star at his best if they want to make some noise in the postseason. That's why they're running back the same playbook they deployed with Kyle Tucker recently, giving him a few days off and hoping the mental and physical break can help him snap out of his funk.

But in the meantime, it does open the door for Alcántara to make an impact at the big-league level. He made his big-league debut late last year and collected his first career hit at Wrigley Field this week and this is his chance to show how his toolsy make-up can translate on the big stage.

Cubs' Kevin Alcántara has a ton of upside; can he make the most of it?

Talent evaluators love his power potential at the dish and his athletic skillset that makes him a solidly above-average defender in the outfield. On the 20-80 scale, MLB Pipeline pegs his running and fielding abilities at a 60 (plus) and his power at 55 (above-average). But there's one huge hole in his game and it could quickly derail his ascent to becoming an everyday player for the Chicago Cubs.

In a recent piece at The Athletic (subscription required), MLB prospects expert Keith Law broke down a handful of recent call-ups, including Alcántara. He said he remains 'bullish' on the Cubs outfielder's potential, but admitted there's work to be done if he's going to stick at the big-league level due to his struggles with offspeed pitches. Law points out a 40 percent whiff rate on breaking pitches at Triple-A coudl lead to MLB arms 'wrecking him' with breaking stuff down the stretch.

It feels like swing-and-miss grows more prevalent in the game with each passing year, but given the severity of Alcántara's struggles with the breaking ball, it feels like opposing teams - especially come October - will know the scouting report and force him to adjust on the fly. If he can't make those tweaks (something he failed to do this year at Iowa), his long-term outlook could quickly sour.