He is a Hall of Famer, a seven time all-star, a six-time 20 game winner, a man that led his team to the pennant as a 23-year-old, made the cover of Time Magazine, and ended up with 286 career wins. Roberts led the league in wins 4 times, strikeouts twice, and complete games five times.
Of course, none of that happened during his short stint with the Cubs.
The Cubs might have seen this interview with Roberts just after the 1965 season, and thought they should give him one last chance. He sure sounded like he still had the fire to pitch.
Unfortunately, he was the oldest player in the majors (39) when he was picked up by the Cubs in 1966, and he didn't have anything left in the tank. The head and heart were willing, but the arm wasn't.
In his nine starts with the Cubs, his ERA was over 6, and he gave up 8 home runs. Those just added to his record setting total. Roberts has given up more home runs than any other pitcher in history. One of his teammates on the 1966 Cubs is now second place on the all-time home run list: Ferguson Jenkins.
The Cubs released Roberts after the season, on October 4, 1966. He never played in the majors again.