It's a small niche market, no doubt. That said, they require a bit more TLC when doing that pre acquisition due diligence.
Look at past .ly sales & trends at dnpric.es. Many more Park.io transactions going to auction. Less common are the $99 transactions (when only back ordered by one user hence no auction). Changes are small, but there is more than likely a correlations. Just my personal take.
Moreover I'd argue that the market for .ly domains is bolstered by recent push by Flippa to cement their status as a real player I'm this space. Kudos to Kevin Fink and all involved, it's been interesting to watch.
And, Park.io has been getting some solid coverage as a reliable .ly backorder service for these domains, in addition to .io, .me and the recently added .to. As competition heats up for auctions there, and the names in turn become more visible to the domaining community, competition increases and affects the overall market accordingly -- however minute I'm this instance (more competition at acquisition stage cause selling point to rise at least somewhat).
As always, just my two cents.