I don't understand how these graphs show brain drain, there a bunch of other explanations. For example maybe a bigger proportion of Germans get an appropriate university degree than Italians. Or maybe the people getting an engineering degree in Italy can't get a job in that field, and end up working on something else but not emigrating. Or the difference comes from non-EU scientists/engineers preferentially moving to UK or Germany when immigrating to the EU.

To show brain drain you really need to look at the migration flows, not a static snapshot of the current populations.