His 4 wins were pretty fortunate TBF retirements in Aus and DC taking Mika out at Austria? and 2 given to him on a plate. Sure he was normally in the points but it was not like today's sport and there was very little challenge to Ferrari and McLaren.
I'm not suggesting he was a contender on his own, just that he was there to pick up the pieces after the mistakes of others (ie consistency). That applied to Frentzen to an extent as well. Still, Irvine had some good runs in the Jaguar when it was a shoddily run outfit.