By now you’ve already noticed that many of your friends and favorite bands have already switched over to the new Timeline format on Facebook. And on March 30, the switch will become mandatory for every page. But will Timeline really have a great impact on how fans interact with music on Facebook? Well as it turns out, it already has had an effect on artists apps…and it doesn’t look pretty.

AppData, an independent application traffic tracking service, has found that the leading Facebook artist page apps (BandPage, ReverbNation, and BandRX) have experienced a staggering decline in monthly active users since February of this year. On top of that, BandPage is currently ranked as the “Top Loser” of the day, while the three apps ranked in the top ten of AppData’s “Top Losers This Week” list. And it’s no coincidence that these decreases occurred right around the time pages started to switch over to Timeline. As Digital Music News points out, the new layout prevents users to make the artist page/app as the default landing spot. Thus, bands can only position these apps as tabs or links within Timeline.

This creates an enormous opportunity for anyone who can find a way to adapt to the new Timeline. However, if the new layout is already having such a downward effect on artists apps, then imagine what could happen when the switch becomes mandatory on Friday. A screenshot of AppData’s findings on Bandpage can be seen above, while ReverbNation (listed as Band Profile) and BandRX findings can be seen after the jump (courtesy of Digital Music News).