So it has always been in a sport whose playmakers might just as well have been dipped in Marmite as linament so precisely do they divide opinions. And the history of rugby is rich in rivalries between those whose instincts led them into acts of buccaneering bravado and those who preferred cautious conservatism instead; a battle between derring-do and derring-don't, you might say.
The last 30 years have delivered a series of examples. Ireland gave us Tony Ward and Ollie Campbell. England produced Stuart Barnes and Rob Andrew. In New Zealand, Carlos Spencer and Andrew Mehrtens each had their followers. Scotland sent forth Gregor Townsend and Craig Chalmers.
The Townsend/Chalmers rivalry burned most brightly 20 years ago, not least because they emerged from Gala and Melrose respectively, two clubs separated by four miles as the crow flies but more than a century of deep-rooted enmity. In truth, neither quite fitted the image created for them – Townsend was a far better kicker than many gave him credit for, while Chalmers had a decent turn of pace – but the caricatures stuck.
And now we have Ruaridh Jackson and Duncan Weir. Jackson is meant to be the mercurial will o' the wisp while Weir is Mr Solidity. At least that's how it seemed until last Sunday, when Weir replaced Jackson in the Scotland side after an hour of the Six Nations match with Ireland at Murrayfield. There was a time when the 21-year-old Weir's role would have been to close the game down; instead, he injected urgency and helped to usher the Scots to victory.
What on earth was going on? Ironically, Townsend is probably the best man to ask, having inherited the services of both players when he took over as Glasgow head coach last summer. Having mentored Jackson in the past, and with his own playing style still a vivid memory, Townsend might have been expected to prefer Jackson's way of doing things. instead, he appears to have added something of himself to Weir, while steering Jackson towards his old mate Chalmers' style of play. "Duncan now feels much more confident about where he is," said Townsend. "You just have to make sure they are improving and taking their opportunities when they have them. Ruaridh took his opportunities leading up to the Six Nations very well in our games against Edinburgh and over at Castres [in the Heineken Cup] as well. I like to think I view them the same as any other players, but obviously I spend more time with a 10 than I would with a prop. I share the bond of having been in that position, so I know what goes through your mind there and what worked for me.
"It was difficult at the weekend. Between them I think they got 12 touches of the ball, and I've seen stats from games where the stand-off got 50 or 60. It's hard to get into a game when you're mainly defending.
"I disagree with the caricatures of them. Both have strengths and both have areas they are working on. It's definitely not as simple as saying one is a kicker and the other attacks better. Duncan's attacking game is really improving, his running on to the ball and his passing, while Ruaridh's kicking game has always been there. He has the length and it's just about making sure he kicks at the right time."
Yet the evidence of last Sunday was that Weir has travelled further in development of his game. Where once he would sit back from the action, he is now more willing to get in among the heavy traffic, where he can ask more questions of opposition defences. Weir credits Townsend for much of that change, although Scott Johnson has also brought pressure to bear to encourage him to play a more attacking game.
"The change of coaching has had an effect," said Weir, who will start for Glasgow against Cardiff on Friday evening. "Gregor has brought other things to the front of my head and other things to work on and focus on. The fact that there are different coaches around is great and I'm just absorbing everything I can and trying to put it into practice."