If you are saying that modern Greeks are not much related racially and ethnically with ancient Hellens you are largely correct. More than slavic and anatolian, todays Greeks are in large assimilated Arvanites and Vlachs.
Arvanites were medieval Orthodox Albanian warriors that with or without permission of the Catalan duchy of Athens and Eastern Roman Empire colonised today's southern Greece in late 1200s and 1400s. Athens in 1833 when King Otto of Bavaria came waaa small village populated by them, They were heavily engaged in the war of 1821 known today as "Greek Revolution" with whom they fought the muslim Ottoman rulers, mainly Albanian Pashas and mercenaries.
Vlachs are a latin speaking people, vulgar latin mostly, a leftover or remains of the Roman Empire era, natives of the Balkans mostly. Today's Romanians are supposed to have originated by them in southern Balkans and came later to Transylvania. Their most known establishment was on Thessaly, it was called '' Great Vllahia'' in the 1200s. They are entirely assimilated on greeks since the region was given to the state in 1882. Besides Thessaly, they were in large numbers eastern Epirus and Macedonia. Many in Bulgaria and Hercegovina too,
So while, you might be correct that modern greeks dont have to do much with the ones of the ancient times, it is not correct to not call them indo europans, Albanians, Vlachs, Slavs are all indo europeans.
Again, indo european is a linguistic label, not racial. Armenians are indo europeans but they are dark and exotic. Hungarians are not, but they are mostly slavic, germanic genetically.