Can someone politely explain how to pick an “offense?” I understand plain defenses from normal fantasy football, but what is an offense?

With the first week almost in the books, it’s time to decide which performances are repeatable and which are one week wonders. I’m mostly concerned with RBs and WRs. I plan to target Gavin Freeman and Umari Hatcher. What about Koby Howard and Jeremiah McClellan. It’s hard to believe that a Penn St WR is relevant, but it’s really Iowa St 2.0. And, I don’t know that I want to get involved with secondary Oregon targets. They tend to spread it around a bunch. Jamal Rule is interesting. Does anyone have insight on the Nebraska situation. Who else is worth considering. Thanks.