You and I have contested this before. Quality > Quantity. Ash's Glalie only battled during the Evergrande Conference but he won/tied in all of his matches and showed himself as a beast. Ash's Gliscor showed his mettle in the very few battles he participated in. The manner in which you win or lose also matters.
Another flaw, the more battles you have, the more likely you will end up with a quality battle and most likely to end up with a lot of quality battles, especially if you are used quite frequently.
I guarantee you that if you switch Staraptor and Swellow generation wise, you would be praising Staraptor and condemning Swellow, and what simply because Swellow had far more battles than Staraptor, increasing its odds of having good quality battles?
Unfortunately, that's just a personal belief. I could also say that Staraptor would pull a Torterra and lose the next fifteen battles, or split them 50-50. In any case, we have to base the argument based on what we saw of Staraptor. I don't see the bird who struggled against Gastrodon, got manhandled by Drapion, and had to go kamikaze-mode to defeat Roserade as one who could have pulled out the same performances that Swellow has done.
I'm pretty sure had Torterra gotten 10 battles in total it would have won all seven.
Okay fine let's look at it like this: If it was ever the case with Swellow (which I'm pretty sure that's not the case), Staraptor has won a battle EVERY match it was in before being knocked out with the exception of Paul. If Swellow did fit that which it doesn't "Morrison's Gligar" there's also Tobias's Latios. Let's exclude the battle with Paul and even Swellow's battle with Latios, and just straight up say: Staraptor is the only bird who has taken out a Pokemon before being taken out itself in every battle. That alone speaks volumes, since when you think of Snorlax, Snorlax is one of his strongest Pokemon because of that fact.
But sure, Staraptor lost to Paul. and Swellow lost to Tobias all without taking a single Pokemon out.
We can't really judge Staraptor on the basis of what its done, when you compare it to Swellow who has had far more battles, and opportunities to have quality battles, because let's say you choose Swellow's five worst battles (the approximate number of battles Staraptor is in), are they superior to Staraptor's battles, or are you going to straight up choose the 5 best battles, and blow Staraptor out of the water. Because if you look at it like that, it's not fair, Staraptor doesn't have the quality because it lacks in quantity.
Sure point to Gliscor who hasn't been used that much, and it having great battles, but let's really look at its record
Tied to Roserade
Beat Bastiodon
Lost to a Snover
Lost to a Torterra
Lost to a Scizor
Beat a Drapion
It's easy to argue that Drapion and Bastiodon are much better Pokemon than Scizor/Torterra/Snover with Roserade being between a win and loss (but acts as a negative point against it) and say that Staraptor is a weaker Pokemon than Gliscor, because of the high esteem that Bastiodon and Drapion are receiving and simply JUST because Gliscor was written to defeat those Pokemon.
But let's look at Roserade shall we. Nando's Roserade definitely is stronger than Barry's Roserade although I'm sure you could argue that's subjective. Staraptor defeated Nando's Roserade, Gliscor only tied with Barry's Roserade. What now? Two Pokemon of the same species from two different trainers battling against two of Ash's Pokemon and Staraptor was the one to defeat the species while the other only managed to tie.
