It was at USC he earned the nickname "Sweet" Musick as he helped lead the Trojans to two Rose Bowl victories and a national championship in 1931. Musick ranks 17th on the Trojans all-time career rushing list with 393 carries for 1,605 yards. While at USC Musick even had a brief flirtation with Hollywood, having an uncredited role along with fellow Trojan players and former player John Wayne in the 1932 movie That's My Boy.
After graduation from USC in 1932, Musick signed with the Boston Redskins (now the Washington Redskins) where he would play for four seasons. Musick led the NFL in rushing in 1933 with 173 carries for 809 yards, an average of 4.7 yards per carry, along with five touchdowns. For these accomplishments he was named to the 1933 NFL All-Star Team. Musick returned to the Redskins in 1935 only to suffer a season-ending knee injury three weeks into the season. In a bid to earn new contract with more money, Musick refused to report for training camp in 1936. The Redskins would not give into the demands and waived Musick. Picked up off waivers by the Green Bay Packers in 1937 Musick prepared to report for training camp however he reinjured the knee while playing badminton two weeks prior to camp, effectively ending his NFL career.