The then-Los Angeles Raiders drafted McKenzie in the 10th round of the 1985 NFL Draft with the 275th overall selection. From 1985 to 1988, McKenzie played as a linebacker for the Los Angeles Raiders. He became a starter as a rookie at inside linebacker next to Matt Millen in a 3–4–4 defensive scheme, playing in all 16 games for a team ending the year with a won–loss record of 12–4, allowing 308 points (19.2 points/game), ninth of 28 teams, and winning the AFC Western Division. Los Angeles lost their divisional round to the 1985 New England Patriots, having difficulty stopping a running game which amassed 156 yards against them, led by Craig James' 104 yards behind an offensive line which featured John Hannah at left guard and Brian Holloway at left tackle. It was McKenzie's only playoff appearance. McKenzie also started all 16 games the following year, but at outside linebacker in a 4–3–4 scheme, with Matt Millen inside and Jerry Robinson on the other side. The Raiders ended with a record of 8–8 and allowed 346 points (21.6 points/game), 19th among 28 teams. He returned as an inside linebacker in a 3–4–4 defensive scheme during the 1987 NFL season, the strike year, but started only five games, sharing time with Jerry Robinson next to Matt Millen, then only three the following year, his final one as a Raider.
