Ah, so you've come across someone that's just ridiculously good (maybe an alt account?) and they just picked some high-combo maps to play on.
If you ever care to peruse the ranking charts some more, you'll see all sorts of trends and player types. (well, depending on how often you like to screw around with comparing numbers and the like)
There are players that seemingly grind away at the same songs over and over again. These people typically have a total score that is much higher than their ranked score. I'm talking like a 10:1 ratio here. Chances are they have a ludicrously high play count relative to others of similar ranking. Guess they got a little TOO frustrated playing a song and kept mashing retry.
Then there are players that have godlike accuracy that approaches or may even be equal to 100%. They may just naturally have the divine gift of rhythm and get it on their first try always, or maybe they're a bit more normal and just keep retrying a song until they get all 300s. The closer their total:ranked score ratio is to 1:1, the more likely it is you're dealing with a god. Please send them a PM informing them that you genuflect in their online presence and wish to have some of their metronome-like perfection rub off on you through hours of potentially painful hell-training.
On the other side of the spectrum are players that make you wonder how they got up to where they are, what with their accuracy being close to 75%. Not exactly sure how they can snag so many points if they're hitting 100s all over the place, but... hey, something must be working for them.
How close can the ranked scores of a player that can decently play a few "difficult" maps (high combos, high potential score per map) and of a player that plays a ton of easier maps (lower combos, low potential score per map) practically perfectly get? This person you've e-stalked via the osu1 rankings likely is one of those high-scoring map players.
...good Lord, did I seriously just write all that?
tl;dr - maybe they're just gold-farming, but clicked on osu! instead of WoW.