If you're training methods are effective then you should be able to do either (see ed's post above).

Criteriums are high speed game of skill, tactics, and daring. You need a full bag of tricks to be consistently good at them. So you need to be able to apply the power to breakaway or jump a gap, you need to spin to recover and rest, you need both for the finishing blast.

If you're only good at one then you will pidgeon-hole yourself into a small range of racing styles. Crafty riders will spot this weakness and exploit it. And they will enjoy making you suffer