That makes sense sure, though I've read that I2a was around in the middle Balkans for near 9000 years, in which case the story of us coming with Slavs is untrue, and most of us are just locals who adapted the Slavic languages. This could explain it:

Some dated information and speculative comments in the quoted text from Eupedia.

Frequencies of I2a2-Dinaric in Slavic populations have been adjusted in recent studies.  Slovenian population has 13% according to the table from an articles published in 2013. Poland, Czech Rep, Slovakia and Russia have similar frequencies as that of Slovenia within a margin of error.

I2a2-Dinaric is a young mutation around 2,550 years of age according to Ken Nordtvedt. It doesn't make sense to discuss Cucuteni-Trypillian culture which is 4,800-3,000 BCE. There are many sister branches of I2a2-Dinaric found all over Europe to British Isles. Besides, no researcher has tested the DNA of  Cucuteni-Trypillian culture people.

«Daco-Thracian and Illyrians having 2-3 times than R1a»  is a speculation at best, as the Y-chrosome markers of Daco-Thracians and Illyrians have not been tested yet. Although, mtDNA of Thracian remains have been tested. As far as I can remember Italians, Albanians and Greeks exhibited greater genetic kinship to Thracians than Bulgarians and Romanians on mtDNA test.

Ken Nordtvedt split I2a2-Dinaric to northern and southern branch. Northern branch was found in south-eastern Poland.

Highest variation of I2a2-Dinaric is found in north-western Ukraine. The region that has a higher
haplotype variation maybe considered as the origin of haplogroup according to research findings of L. Zhivotosky.

R1a-Z282 / R-M420 (east/central European branch)cannot be attributed to Slavic populations alone.

Finno-Ugric populations:

Estonians –  – 33%, Vepsian — 36%, Karelians — 41%, Mari — 31.4%, Komi — 37%.  Erzya have a high frequecy. Hungarians — 55%.

Balts : Lithuania — 45%. South-eastern Lithuania — 62%. Latvia around 40%.

Mutation of R-M420 is older than modern  ethnicities. Besides, proto-Slavs,  the community of first linguistic shifters from proto-Balto-Slavic community could not have possibly have a single haplgroup in male population. Although, R1a may had been the dominant one.

Today, in  most Slavic countries  a typical mix is R-M420 + I-M423 ~70%-75% . Both are equally Slavic with I-M423 more frequenty in southern Slavic countries, while R1a in northern Slavic countries.