tempered flesh (jewel medium aoe)

So I'm running a righteous fire build, and was hoping to use this jewel for a significant regen boost. But after equipping it, covering 4 +10 str nodes in the AoE, my regen is actually *reduced*. What's up with that? Sure it takes away 40 strength and a small bit of life, but going from 325 to 285 strength surely shouldn't equate to that significant regen reduction?

https://pathofexile.gamepedia.com/Tempered_Flesh

Tempered Flesh
Crimson Jewel
Radius: Medium (1200)
-1 Strength per 1 Strength on Allocated Passives in Radius
2% increased Life Recovery Rate per 10 Strength on Allocated Passives in Radius