Rolling Reputation Number? WTF is Going On?

So I was checking out a new Steemians account, looking at one of their two posts, and something weird caught my eye. Their Reputation Score was changing before my eyes, just like a rolling odometer. I probably wouldn't have even notice their Reputation Score if I hadn't watched it go from 52,to 52.5, to 53, then 53.5 and so forth until it finally ended on 55.2. I had never seen something like that happen, so I started checking the account to see how one might increase a score like that. That kind of information could come in handy.

But here's the thing. This new Steemian has been here only two days, has made 5 posts, most of those being comments or replies. Only two of their posts were original root posts. They only have 3.6 SP, 2.791 STEEM and $1.4 SBD's. The two root posts have about 100 upvotes and just under $400 in curration that has yet to be paid. They paid some good STEEM for bot upvotes for the two root posts.

But how did their Reputation Score ratchet up like the spin wheel on a slot machine?

Something seems off, but it is very possible that I don't know enough about Steemit yet to say so for sure. All I can say is that I've never seen it, never heard someone give advice on how to do something like this or have experienced anything like it in my own account. I've been here 60 days now, made 141 posts (about a third of those being original root posts) and spent hundreds of dollars promoting my posts thus earning hundreds of dollars in curration too. And yet, my Reputation Score is no better than this new, two-day old account.

Again, I'm not accusing anybody of wrong doing, I would just like to know the mechanism of how this works. I was under the impression that Reputation was based on the amount of time an account is active and how many posts, root posts being favored, one makes more than anything else. But that doesn't seem to be the case. Or at least not in this case. I've included a screenshot above, but have blanked out any identifying information. I'm not looking to throw anybody under the bus, I just want to understand how it all works.

If anyone has an answer or explanation, please let me know in the comments. Thanks!