Let's begin with some numbers:
1 level of Stats: +115 HP / +0,18 HPS / +105 Mana / +0,32 MPS / +25 armor / +6 Weapon damage / +2% Attack speed
3 levels of Stats: +345 HP / +0,54 HPS / +315 Mana / +0,96 MPS / +75 armor / +18 Weapon damage / +6% Attack speed
6 levels of Stats: +690 HP / +1,08 HPS / +630 Mana / +1,92 MPS / +150 armor / +36 Weapon damage / +12% Attack speed
Always keep in mind during this analysis that you can't reach level 5 of stats before level 10 and level 6 of stats before level 15!
These numbers are NOT progressive, each step is totally the same as the one before and the one that will follow. So gaining these stats points when you're a weak level 1 DG is much better than a strong level 15 DG, right? Gaining +115 HP when you got around 1500 HP is more important than gaining +115 HP when you got around 4500 HP. This means, the more you wait, the less effective it is.
Let's take an example, a level 6 assassin DG spent 3 points on Stats (half of his levels), he will get these advantages:
+0,54 HPS & +0,96 MPS ... +32,4 HP in one min & 57,6 Mana per minute (for example, Venom Spit II is 650 mana, so you have to wait more than eleven minutes to get a "free Venom Spit II") => totally useless
+75 armor ... doesn't seem very much... Have you noticed a 1500 armor item gives you ten times this protection? (AND 500 Health) => useless
+345 HP ... OK, this is never useless BUT this is a matter of two AA, it won't make a significant difference
+315 Mana ... Half of a Heal III by Sedna, this is not that bad, but just one half-spell free
+18 Weapon damage ... Far less better than a 400 gauntlet item.
+6% Attack speed ... This can be great for DG who relies on AA
I mean, this is always better than nothing. Having +345 HP is better than +0 HP but sacrificing 3 level points for the combinaison of very little bonuses... Is this really efficient?
It's very difficult to estimate with precision the impact of Stats point, because it will depend on your skill, your opponent's and ally's ones, the DG choosen, the gears choosen and so on... Can you really say "yeah, these 4 points of Stats really help me in this duel at that moment of the game!" ?? Are you sure, in a perfect mirror match, with the only difference the opponent choose other skills than stats, you would have won??
I made a test: if stats points are stronger at the beginning of the game, why not trying to boost them asap? I wanted a strong AA DG for this, with passive abilities so I chosse Rook (but I could have choosen UB) and follow this strategy: trying to max stats, choosing 0 ability that requires mana (except one point in Boulder Roll for interrupt) and with no mana items, buying only HP/armor or damage. Here's the build I've tried:
Starting with BotF, Banded armor + Scalemail
lvl 1 save
lvl 2 Stats + Archer Tower
lvl 3 save
lvl 4 Stats
lvl 5 God Strength + Boulder Roll
lvl 6 Tower of Light
lvl 7 Stats
lvl 8 Stats
lvl 9 Trebuchet
lvl 10 God Strength
and the result was... really terrible! I got my ass kicked altought non-tower Rook is one of my best DG. My conclusion was "no hammer = lose".
Some of you will argue "yeah, you can't compare Stats to Hammer Slam", but that's just an example, and my point is, finally, Stats are not good at all in comparaison of what you gain by sacrificing skill points.
The only time I now choose to take Stats is if I know I have no other useful abilities to take, right now or even in future.
What's your opinion about that? Have you ever been depited by the use of Stats points?