Attachment 12833
I knew that the awkwardness of talking about "east shift" when one refers to an upward translation in a PCA because the samples the shifted ones are pulled towards are geographically from east Europe would confuse some that would start talking of this "east shift" as the signal of a Near Eastern gene flow, that is what you'd expect from the reasons you've brought, but that would translate into a rightward translation in the PCA, that is towards the MENA groups, but what we see is an upward translation.
The Italic peoples of Italy were more "west-med" that modern Italians, in the sense they were more downward shifted than them, but the Daunian samples are roughly as much rightshifted as today north Apulians and a few as south Italians, and a few samples from Italy have a rather upward shifted position compared to the bulk of the samples from their regions, so it cmay mean that the gene flow that upward shifted Italians had been trickling down in Italy from SE europe since ancient times, though of course only future studies will tell.
Besides that remark, the haplos and the admixture models do not really back up that scenario of significant steady genetic shifts due to migrants from around the mediterranean and from northern Europe.