Unfortunately, 2 years on the Tiger, unless it's kept on a trickle charger in a garage, seems to be about typical. Plus you don't know how well the battery was kept when new in the showroom or how long. Tigers do seem to have some kinds of parasitic draw, or maybe the stepper motor just goes mad. You haven't been just going out to the bike and switching on / switching off? Activates the stepper motor each time.
So .... you can charge, test, etc, but there'll always be a concern there. I would just replace it with a higher-spec one. TB bought what looked like a very good and more powerful alternative recently, a Motobatt I believe. Or MDS Battery has a good range of types for the Tiger - I've used them and they're good, on advice too.