Kacy Clemens -- son of MLB legend Roger Clemens -- says bouncers at a Houston bar beat him so badly during a New Year's Eve event, they may have destroyed his pro baseball career.

Clemens and his pal, Conner Capel, have sued the Concrete Cowboy in Texas -- claiming they were just hanging out when bouncers singled them out and ordered them to move out of a spot in the bar while they were trying to order their first drink of the night.

Both men are minor league baseball players -- Kacy is a 1st baseman in the Blue Jays organization and Conner is an outfielder with the Cardinals organization.

The guys claim they complied with the bouncers' orders -- but the hired muscle manhandled them anyway, eventually beating them so ferociously they sustained serious damage to their faces and bodies.

In fact, Conner says he suffered a fractured skull -- and took photos of the bloody aftermath.

A lawyer for the alleged victims has suggested Kacy may have injured his throwing arm in the incident. He also claims Conner will have to see a neurologist for at least 5 years.

According to the lawsuit, cops showed up at the bar that night and determined neither Kacy nor Conner were intoxicated. One of the bouncers was arrested for assault.