Yes, Leipzig has lost a lot of points in the last few matches. Leipzig has experienced 3 consecutive defeats, 1 draw and 1 win, where Leipzig has lost 11 points. Therefore Leipzig is quite far behind the top 3 clubs. Even though Leipzig still has the opportunity to occupy the top 3 rankings its performance Leipzig's is are still quite doubtful and unstable, but at least Leipzig can break the series of bad results in the last few matches by winning the match against Union Berlin in week 20.
Union Berlin not only experienced a slight setback but experienced a very drastic decline, in fact I didn't expected Union Berlin to experience a very bad season this season because last season Union Berlin was ranked in the top 4, while this season Union Berlin had to fight to avoid the relegation zone because his current position is very insecure with clubs that are in the relegation zone because he is currently rankings 15th out of 18 clubs.
Leipzig has been performing well of recent in their league and comparing them to their last encounter they've been to a reasonable extent better than them in the ball play, dominance, victory and goal scoring opportunities and abilities. Leipzig now rubs shoulders with the likes of Bayern Munich, Dortmund who are amongst the tough clubs in the league.
Leipzig does have a big chance against teams in the league and their victory in the coming games won't be surprising because they're the stronger team. Not withstanding, these teams should be able to play not forgetting that they still have games left for a couple of weeks in the league too and there shouldn't be resilience. They'll be facing who are in 13th position on the standings, in their next fixture. Augsburg might be very distant from them, on the standings, however they're not a team to be underestimated.