Plutarch and Appian said Hannibal considered Pyrrhus the greatest commander the world had ever seen after Alexander, which isn't that big of a stretch at the time.

Keep in mind there weren't too many "greatest commanders" during this period to draw from, and Pyrrhus apparently wrote a text on waging war which was quite popular but lost to us.

The fact is he defeated the Romans several times, even when outnumbered, subjugated most of Sicily, and was still called to fight all over Greece. He was obviously well respected in his time. The fact that he was unable to hold on to any of his conquests points to him as less than stellar governor, but on the battlefield he had quite a good record.

He probably wouldn't rank up there now with another 2000 years of history to draw from, but back in those days he was by far one of the most respected generals to have lived in the area.

Could you maybe describe where you are getting that notion from? It is my understanding that Pyrrhus very much wanted to emulate Alexander but his track record was, as you note, far from spectacular. He is obviously most famous as the origin of the term pyrrhic victory but that's obviously not a very flattering legacy. Nor sure where he is praised up there with the likes of Hannibal or Alexander