There are also cases, like myself, where they've been spectating for a while and only chose to jump in later. I've been watching matches since the game came out but didn't buy the game until last month. Due to that, I have a good knowledge of what to do for each stage, mode, and weapon (except Hammerhead Bridge), though I obviously wouldn't have the skill to execute it all.
I didn't expect anyone to go easy on me (most of all because it was during a Splatfest, but even without that factor, it would've been the same), though I wouldn't have minded if someone did. This is a game where even the most unskilled of players can still contribute and help out.
These were the results of my very first match--no alt accounts here. The downside is that I haven't really gotten much better than that. But I know as a fact that most Level 1 players do not win their first match and will usually start with quite the losing streak, and that most people haven't been spectating and observing as much as I had.