Kumble has better average in wins than Warne
Flower had better average in wins than Lara
You win more matches against weaker teams and in favourable conditions. Completely useless in determining who was a better match winner.
I wasn't listing avg in away wins. You can pick up 2 wickets at 20 and gets counted in win stats. I was talking about outsized efforts like 5-fers in wins. You took a 5-fer and if your team wins then you did have result changing 5-fers. Yes, there will be 3-fers with impact but it will be true for all bowlers. 5-fers is just a short cut and a good one. There is a reason that among the top 5 in history, we are seeing usual suspects like Marshall, Hadlee, McGrath, Steyn in pacers list. Random bowlers are not showing up in top 5 list.
Kumble has 4 5-fers in away wins and Warne has 12. Yes, Warne did have a better team to win often, but if we are going into discussion on who had more impact away from home in changing the result then answer is clearly Warne. Other factors like away avg, 5-fers in away etc can be looked to say which bowler did better.
I wouldn't use tons in wins in test for batsmen the same way 5-fers in win for bowlers. You have to take 20 wickets pretty much all the time to win tests. You win test by taking 20 wickets cheaper than your opposition. In shorter formats, it's other way around. You can win by scoring more than opposition without taking any wicket in the match. You can't win tests without takign a single wicket. Relative importance of batsmen and bowlers are different in winning longer formats versus shorter formats.
Batsmen and bowlers, both are important, but relatively, bowlers will win you tests more often than batsmen with outsized efforts. It's other way around in shorter formats. That's the reason, India won rarely tests in sena before bowling became good for sena conditions, but won won plenty in shorter formats due to good batting.
Again these are just short cuts, but a good one. It shoudn't be used to start ranking players without looking at their over all career record.