Efteling actually is one of the biggest parks in Europe.
It's even bigger than Disney Land in Paris (72 > 56 ha)
In my opinion, Efteling needs a thrill ride. They only have Joris and de Draak and de Python, and even those rides aren't very spectacular. But then again, Efteling isn't about thrills.
I don't think when he said smaller he was referring to the physical size but to the fact it is less visited then other parks in Europe.