His team has certainly made life tough over the years on the conference's leading scorer, Roberto Nelson.
Johnson and the third-ranked Wildcats look to shut down Nelson again in Wednesday night's matchup at Oregon State.
Arizona (27-2, 14-2) clinched the Pac-12 regular-season crown with its fourth straight win, 79-66 over Stanford in Sunday's home finale. Freshman Aaron Gordon led the way with 19 points and 15 rebounds.
''It feels good,'' Gordon said, ''but it's not the final stop on our destination.''
The team-oriented Wildcats have four players who average double figures in points, led by Johnson's 16.0 per game that barely puts him within the conference's top 10.
Miller believes that the junior's defense and leadership are also reasons why Johnson deserves the honor as the conference's best player.
"He has had a phenomenal season," Miller said. "What he does on defense, that alone, I think he's an all-defensive team guy, one of the best defensive guards that probably plays in college basketball. And then from an offensive perspective, he's our leading scorer."
Nelson is averaging 20.6 points but likely isn't a contender since Oregon State (15-13, 7-9) is in 10th place in the Pac-12.
The senior guard has had trouble in his career against the Wildcats, averaging 7.4 points on 30.2 percent shooting in seven games for his worst figures against a conference opponent.
Nelson also leads the conference with 7.8 free-throw attempts per game, but he's totaled 19 foul shots in this series. Arizona commits a Pac-12-low 16.4 fouls per game.
The Wildcats are among the nation's best defensive teams, limiting opponents to a Pac-12-best 38.3 percent from the field. The Beavers shoot 48.3 percent for one of the conference's best marks.
Johnson and Nelson each finished with 10 points in Arizona's 76-54 home rout Feb. 9 for its sixth straight win in the series. Gordon scored 17 and Rondae Hollis-Jefferson added 16 as the Wildcats enjoyed a 39-24 advantage on the glass.
Arizona leads the Pac-12 in rebound margin at plus-9.2. Oregon State big men Angus Brandt, Eric Moreland and Devon Collier combined for 13 rebounds in the first meeting, but Miller is wary of that trio.
"If you look at Oregon State and that's our next game, they have some seniors who are playing their last games at home and there's a lot of pride with that and by the way, they're also talented, physical big players in talking about Brandt and Collier and you have Moreland, who's a year younger," Miller said.
The Beavers lost for the fifth time in seven games, 74-69 at UCLA on Sunday. Nelson scored 23 for Oregon State, which made 14 of 23 foul shots and had 16 turnovers that led to 20 points for the Bruins.
"You can't turn the ball over like we did and expect to win the game," coach Craig Robinson said. "If you take the combination of points off turnovers plus our missed foul shots, we really shot ourselves in the foot."
These teams both average 14.4 3-point attempts for the Pac-12's lowest mark.