No Bronk, that's just what you think, that doesn't in fact make it so.
Guppy, the actual group, I don't know the numbers/names. Some group in the PTO. They wanted plane X (where X is better than the P39) because they wanted to get away from the P39. They were told that planes were in short supply and they'd fly what they had until they were no longer servicable. So they took that opportunity to ding them up every mission, to crash land them, to bail from them when the engines ran a little hot, anything to get rid of them.
This from somebody elses posts here on these forums a long time back. They were quoting a book when they posted.
As for low-down, sure it could fly better at lower altitudes, because the lack of a supercharger, but it has fairly bad instability in every flight sim game that has EVER modeled it, it's slow and sluggish even low down (albeit far far far worse up high). I don't think we can use pilot comments about "This was the best plane of the war" because many many posts over many many years have argued that any pilot will have a bias towards any plane that got him home alive, no matter how poorly the plane actually flew.
Sorry for not remembering the group in the story above. I've got one of those memories that remembers details and facts quite well, but not the dates or names that go with them.