@RobbyBevard:
Again, they aren't going to SAY "Yeah, it's beating One Piece!" they're just going to say "It's the number 1 spot." Its up to the reader to assume what the number 2 is in the year 2015, or whenever they are currently.
Even in real Jump, OP is number 2 occasionally. A flux of 10 or 20 votes isn't a huge deal.
Now, if all the characters in the series suddenly had the top 5 slots, that'd be pushing it. But Eiji, the super genius? After 6 years of producing a series? 2 at once for a large chunk of that? And him intentionally slowing down and trying even harder after being stuck at 2 for a long time? That's fine.
All right let's look at the six main Jump mangaka in the series. Ashirogi Muto, Nizuma, Hiramaru, Iwase, Fukuda and Aoki.
Detective Trap was quite popular before Mashiro's hospitalization and was a top ten main stay, but after Mashiro's accident it never fully recovered and it was canned. Tanto never really worked and certainly wasn't a hit (DAMN YOU MIURA!) and now we have PCP which is again a top ten mainstay even scoring in the top five quite a bit.
Nizuma is the only mangaka (besides Iwase but she's the most recent addition) to only have to work on one series, Crow which as you said is pretty much always 2nd and Nizuma is currently trying to get it to 1st. Hiramaru used to have Otters 11 which if I recall correctly was usually in the top 5 series and was one of Jumps heavy hitters in this fictional universe. Currently Hiramaru doesn't have a series but he's going to start one (I might be wrong about that though, I thought he did start a new series but Bakuman Wiki told me otherwise). I think it would be better if he doesn't have a series because that would mean more competition in the rankings for Ashirogi when he starts his series again. Drama.
Then we have Iwase who's series +Natural was a top ten, even top five mainstay, after all it got an anime really quickly. Fukuda had Kiyoshi Knight which was usually in the top ten and only near the tail end of its run slipped away (iirc). Then we have Road Racer Giri which I think is also a top ten mainstay (after all it has an anime, which is pretty hard to get without being consistently in the top ten of a magazine.) Aoki is the least popular of the main mangaka from what we've seen with Hideout Door at first being in the top ten but soon enough it slipped away and was canceled (weird since Takagi said it was really good) and then there was that Green Leaves manga which she didn't like writing too much and it was also cancelled and now she's working on a new series again.
The point of all this is that Ashirogi and Eiji aren't the only two mangaka that have almost always been in the top ten of this fictional universe. Iwase, Fukuda and Hiramaru are also consistently in the top ten, even top five. That means about half of the top ten in Jump in this fictional universe is fictional series (but that's not too bad because I imagine most of Jumps heavy hitters currently would be finished by then Naruto and Gintama would be finished, Bakuman doesn't exist in this universe obviously and Bleach and Reborn aren't heavy hitters anymore which leads me to believe they'd be cancelled by now, I like to think that the "big 3" in this universe are One Piece, Toriko and Crow which is probably a much better big 3 then the "big 3" we used to have for so long).