I think it would be pretty useful to see things such as your median or average XPM/GPM (and/or K+A/D) on the graph that is viewable on the hero stats page.

eg (not to scale)

graph_idea_median.png

Alternatively/additionally, some other lines such as trend lines for those things would be pretty useful - as would showing the patch releases in the background as shaded areas.

Basically more stats! I know Dotabuff exists and does a good job but there's just a huge potential to show this stuff in client that isn't exploited, and Dotabuff doesn't show enough 'personal progress' graphing, so there's a gap there for some basic implementation of this.

One of the stats I have personally found informative is
- XPM/GPM as a % of team/enemy team/match XPM/GPM

Not currently included on other sites. Essentially each Dota match has a pretty individual profile in terms of how much gold and xp players accumulate (also KDA), and so it's useful to be able to see both those stats in the context of each match. It's arguably more useful to see that you used to be getting 50% xpm versus everyone else in a match, but now, x months or years later, you're getting 105%.

The same is true of other things like fight participation.

edit: if anyone wants to calculate these things for themselves I recommend taking a look at the Dota API and plugging it into Google Sheets or your own apps.