Some parts taken from this Huffington Post article from May of 2014 (click on link to read entire article)
The same goes for Olivia, when the writers included her childhood trauma only when it related to a case, or when a victim reminded her of her own upsetting birth story. We only learned about Munch’s mentally unstable ex-wife Gwen when he needed to get her help on a case, and Fin’s son was only a major part of an episode when he ended up being involved in an investigation, or when his sexuality reflected Fin's struggle with acceptance. The writers managed to give us stories about a squad of relatable characters who evaded their own issues by attempting to assuage the pain of others. But when the lines become blurred between personal and professional, and when the detectives’ struggles take precedence over the victims' "SVU" turns into an entirely different show. Nothing describes Season 15 better than that.
In the second half of the season alone, all three major characters experience their largest downfalls yet and each are brought to their absolute lowest. Benson, Amaro, and Rollins were all on the brink of losing their badges this season, with two of them getting investigated by Internal Affairs (IAB) within the span of four episodes. In the past, IAB's investigations of the squad have been rare but serious occurrences. This season both Benson and Amaro's cases were amplified and then immediately swept away and forgotten by episodes' end. Beyond this, many of this season's storylines felt tenuous and hollow. Amaro was nothing more than a carbon copy of Elliot, with his similar anger management and marriage troubles. As if that drama weren't enough to incite viewers, this season added an even more unexplained and impractical side story of Amaro and Rollins' affair, which was never alluded to before nor resolved after. Season 15 overall was filled with dramatized, haphazard vignettes revolving solely around the detectives' personal lives. In retrospect, those episodes stand out far more than any of the criminal cases, many of which are hardly memorable.