Grigas was an oustanding running back and three-year starter for the Crusaders. He twice made All-New England and All-East and received recognition on several All-American teams. As a sophomore, Grigas led the Crusaders in rushing with 437 yards. He began his junior year by scoring all three HC touchdowns as the Crusaders upset LSU 19-13. His 826 rushing yards that year were the fourth-best in the nation. He was injured for much of his senior season, but he did manage to throw two touchdown passes (and ran for two more) in HC's 55-12 upset over Boston College. After graduation, Grigas was drafted by the Chicago Cardinals in the 2nd round of the NFL draft. He played five season of pro ball. In 1944 he led the NFL in touches (215),as he ran for 610 yards on 185 carries, returned 28 kicks and caught two passes. He also threw for 690 yards on 131 pass attempts that year. He was a First Team All-NFL selection that season.