I also think the h2h is underrated a bit as there are many examples of players who just can't win against particular opponents and definetly should be a factor which should be taken into consideration when backing a player
If there is a differential in the H2H, particularly when it's hard to work out why, I use that to filter out a bet rather than to make one.
Player history is a reasonable one. Some guys just play well in certain zones. You've got the early season peaker that's always up for the first few tournies of the year, some European clay courters are no good in South America and vice versa, some guys play a lot better on US hardcourts than European ones.