A decent footballer rarely needs to tackle, their positional sense and reading of the game can mean it's not required. That's why Millar often intercepts things instead. Paton on the other hand continually gets caught on the wrong side of the ball before forlornly chasing after it and perhaps launching into a "tackle", more likely a foul. You could make a case for Davidson being our best midfielder but Millar is clearly better than anyone else in there. Davidson is also at his most effective alongside Millar. Tackling is of course a great strength of Davidson's but a lot of them are of his own choosing rather than being caught out as such. The two of them offer a good balance.