Meanwhile some Eurozone countries like Greece, Italy and Spain actually saw a decline.
Hard not to draw such conclusions when your set includes all the troubled countries and none of the fast growing ones.
That isn't some coincidence. The biggest beneficiary of the Eurozone relies on the suffering of its less successful members and this is ultimately reflected by the fact that poorer countries in the Eurozone don't catch up with the rest of the EU and in fact the opposite happens. Meanwhile for EU countries outside the Eurozone it is smooth sailing because they don't have to suffer for the benefit of a country that is role playing as the hero of the Eurozone.
With this I'm glad my country doesn't qualify - I'll take that any day vs having monetary policy tied to that of a very different economy.
EE countries which adopted the Euro did quite good as well. For instance growth in Poland lagged significantly behind Estonia or Lithuania in the last 10 years or so.
IMO this is a better comparison than with Poland and the Baltics since Poland is a massive country and has 5x the population so there are a lot more factors at play.