(CNN) -- National Football League Commissioner Roger Goodell slapped Pittsburgh Steelers quarterback Ben Roethlisberger with a six-game suspension for "conduct detrimental to the NFL" on Wednesday, calling it "the best step for your personal and professional welfare."
Roethlisberger, who led the Steelers to Super Bowl titles in 2006 and 2009, faced the threat of criminal charges after a woman accused him of raping her in a Milledgeville, Georgia, bar in March. The quarterback's lawyer said no sexual assault took place, and prosecutors decided last week that they could not prove that a crime had been committed.
Goodell ordered Roethlisberger to undergo a "comprehensive behavioral evaluation by medical professionals" and follow their recommendations "to help him make better decisions and avoid situations that can cause legal or other problems."
If he follows the recommendations, the suspension could be cut to four games, but if he doesn't, it could be extended, the league said. If he misses all six games, it could cost Roethlisberger an estimated $2.8 million, according to The Associated Press.
In suspending Roethlisberger, Goodell said that nothing about his conduct "can remotely be described as admirable, responsible or consistent with either the values of the league or the expectations of our fans."
"Your conduct raises sufficient concerns that I believe effective intervention now is the best step for your personal and professional welfare," Goodell said in a letter accompanying the suspension. He urged Roethlisberger "to take full advantage of this opportunity to get your life and career back on track."
Although prosecutors determined that no charges would be filed, the investigation showed that Roethlisberger "contributed to the irresponsible consumption of alcohol by purchasing (or facilitating the purchase of) alcoholic beverages for underage college students, at least some of whom were likely already intoxicated," Goodell wrote.
"There is no question that the excessive consumption of alcohol that evening put the students and yourself at risk," he wrote.
Roethlisberger was accused of sexually assaulting a woman in the bathroom of a nightspot in Milledgeville, about 115 miles southeast of Atlanta. The 28-year-old quarterback owns a home on a nearby lake.
Fred Bright, the district attorney in Milledgeville, said at a news conference announcing the decision that Roethlisberger should "grow up." But, he said, "We do not prosecute morals. We prosecute crimes."