No, Mitchell was slicker and had faster feet. Corley punched harder, was more durable, and had better counterpunching. Mitchell had Don King backing him and making things fall into place if I remember right. Corley had limited management but still beat Bailey, which is the best win between the two of them, and was competitive with Judah. He also gave Mayweather more problems than Mitchell.
I'd put him above Corley, but there's not a huge gap. Corley had more pop and a better chin. Mitchell was faster (of both hand and foot) and a bit slicker. Judah was a bit higher class than both, so I'd rank them Judah>Mitchell>Corley.
Mitchell was past his prime when he fought Mayweather though he even in his prime he still doesn't beat Mayweather.
Nice analysis another thing is Mitchell was smart enough to retire before random journeyman started to beat him.