Some observing players may have noticed, that the amount of skill rank points you actually receive varies from fight to fight. The reason behind this is a complex calculation depending on many parameters, e.g. your current skill rank, hero level and your opponents skill rank.
Please also note, that the tool tip only shows the average points, you should receive for a win at your skill rank and level! The opponents skill rank is not considered here, so the points you are actually getting for a win are probably higher or lower, depending on your opponent.
Example: Player A (skill rank 30) wins a fight against Player B (skill rank 27). Before the fight, Player A's tool tip says, he should receive 11 rank points on average for a win, but he will effectively only get 7 points. The reason is that Player B's skill rank is way lower compared to Player A's skill rank, so Player A will be awarded with less than average rank points for this fight.
Also be aware, that the tool tip always shows the needed points to reach the next rank to your highest reached rank. Your highest reached rank does not have to be your current rank, e.g. if you have lost some fights, your current rank will probably be lower than your highest reached rank. For the calculation we always use your current rank.