Frentzen/Villeneuve
Yeah with Frentzen, I certainly estimate he was better than Villeneuve from 2001 onwards. Well I'm not sure about 2001 since HHF had some dud races like spinning in France and somehow only finishing 7th at Silverstone behind the Saubers after qualifying 5th (Trulli started 4th) - despite Coulthard Trulli and Ralf all retiring. His races seemed to lack in the Prost too, though his qualifying was immediately a big improvement over Alesi. Villeneuve got podiums and 4th in Monaco, so his races seemed good even though his qualifying was bad (JV still outqualified Panis 12-5 though, strangely). I also remember Jacques saying he drove a perfect race at the Nurburgring, yet for all that it only translated to 9th so no-one noticed. There was also a collision between the BARs at the start at Silverstone, which had Panis furious. He even suspected it might not have been totally accidental!
I think Villeneuve did better than Frentzen in 2000 and was slightly quicker in 1999 imo, though he had nowhere near the points gathering ability of Frentzen, even taking into account his terrible unreliability imo.
Even in 2000 Jacques could still be daft in races. Canada seemed to sum up what he was about. He started 6th, made a great start and was running in the top 3 for a good while early on, right up with MS and Hakkinen, which was exciting! Then later on, when it was wet, he T-Boned Ralf at the hairpin in the true spirit of Maldonado. That's why the hairpin got moved back from the following season IIRC, to give drivers more run off if they crash.
Now you mention it, I remember the great Villeneuve starts from 2001 very well! I remember Autosport or somewhere saying it was because Jacques set his car up with a long 1st gear for races, even though that would compromise his overall performance. He figured since he was never really going to beat the McLarens and Ferraris, the long 1st gear would help him get a great start ahead of all the other best of the rest runners, where he could then spend the rest of the race holding them up. Honda power helped at the time, since they had 800bhp (more than they have now I bet), one of the most powerful engines going.
The definitive example of this for me was always Imola 2001, where Jacques started 9th, drove past the rest at the start then spent the race holding onto 5th, despite huge pressure from his friend Salo (another @sshole to be frank, though I liked him).
Eddie Irvine
With Eddie, yeah Pedro de la Rosa, recently having joined Jaguar, outqualified him 6 times in a row mid season in 2001, at exactly the time Irvine declared he was the 2nd best driver in the world and "quicker than Mika"! He did claim he was having a bad run of things at the time, which was maybe partly true, though he was very quick to point out (more than once over those years) that during their entire time at Jaguar together, de la Rosa never once finished a race ahead of Irvine. Amazingly this is true! Irvine really did have a great knack in later years of getting the result that was possible (scarce as those chances were) when you couldn't trust PDLR to do the same.
Olivier Panis
I so remember Panis qualifying 3rd in that Toyota at Indy 2003. It wowed us back home. It caused such a stir that ITV opened their race coverage with the end of Panis' lap the previous day. There was talk of a BIG result for Panis that day, especially with the rain, but no, Toyota threw the result away with absurd strategy that would make the current Mercedes pitwall look like Ross Brawn, and Panis trailed home 9th out of the points. They then locked out the 2nd row in Japan, with da Matta 3rd this time, only to convert it into a measly 7th and 10th. Still it led to me expecting big things from Toyota in 2004.