It was only 6 draws Leverkusen recorded last season and they didn't lose a single match which means they won 28 games summing it up to 34 matches played. This season they have drawn 5 games and lost 1 out of 15 matches played which is not the same as last season. Leverkusen has a nice standing though at the second position as Frankfurt are not looking as a threat at the moment.
Leverkusen keeping good position in the table is as a result of poor competition in the league. Leverkusen has overtaken Dortmund who used to be second best in the league. Dortmund might not be in the top 4 at the time but that doesn't mean it will be an easy game for Leverkusen when the meet this coming week.
However, the gap needs to be considered as well. Considering they won the title with 90 points, and Bayern was at 73 points, that would mean if Leverkusen was 74 points they could have still won.
In theory of course, if they were that close, maybe Bayern would have played a bit better on a few games too, but I am just talking about theory here. So that means, Leverkusen could have lost 16 more points, and still would have won the league, meaning that if they lose 5 more games, compared to last season, they would still be breaking last years Bayerns points totals. So this is why, it is not about getting 90 points like last year for Leverkusen, it's about getting more points than Bayern Munich, so if they end up playing good enough, there is still a chance.