Because those 2 points and that great run was achieved facing mainly bottom half teams at home and dropping almost all the points they could have done away from home in any conceptually difficult game. If it was a really great run, they would have done more than simply taking advantage of a Spurs team with AVB on his last legs.
If they finish ahead of us, no doubt they will have deserved it, but right now they very much remind me of us in 11/12. If we look at it like being at home gives you some advantage - let's give it a numerical value of likelihood of a win = + 5. Let's say playing bottom half teams at home also gives you an advantage - let's say + 10. So if you're playing at home, against a bottom half team, you're on a + 15 likelihood of winning the match.
So far this season they've had the benefit of playing most matches they were more likely to win in the first half of the season, and were still only 5th at the half way stage. Now they are going to be playing fellow top 4 contenders at home, so there won't be any more + 15 matches. More like + 6 or +7 because their opponents in those games will also have a pretty strong chance of taking something considering their strength. They'll also then be facing teams away who will be getting their acts together - perhaps they have sacked under performing managers and are now well drilled into a plan to stay in this league. I think they'll drop more points there.
They've had a first half of the season playing most matches they were extremely likely to win, and pretty much dropped all the points they were expected to in games they were likely to do so. If they do end up finishing 4th, they will deserve lots of praise and Rodgers will have done a damn fine job. I'd be pretty surprised if they do so though considering how their fixtures have been laid out.