I was used to brewing with pellets and didnt even use a strainer. I just whirlpooled and drained through my CFC and everything was cool. Just tried Whole hops first time and EVERYTHING clogged up, so you really want a bag or a good strainer
You're going to need to strain them. They clogged up my auto siphon after about 1 gallon of transfer and then I had to deal with washing and sanitizing a strainer and a funnel.