as far as I know , the type of music Suga Shikao does for the past 15 years has never been mainstream & it's also difficult to classify his music style too
If you see his Oricon charting performance (
http://www.oricon.co.jp/prof/artist/92474/) , it has always been OK , neither good or bad
at least he's still releasing music & what he does , he does it best . I can't think of another artiste whose has the same style as him & of course he score brownie points for writing/composing ARASHI's Aozora Pedal & writing KAT-TUN's Real Face in which both his self covers for these 2 songs are amazing
Heck , I think his cover of Aozora Pedal is way better than what ARASHI released