That's a great deal, given how contracts are being handed out I'd say fair value for him would be about 15/year, maybe slightly less because Deion Jones got about 14.5. A shade under 13 is excellent value for sure.
What Stephen has to get through his head though is that every deal doesn't have to be a value deal. They tagged Lawrence, played the year out, bullshitted with him for several more months, tagged him again, things got contentious and eventually they gave him a fair market deal.
If you can get it, great, but if a guy is willing to take a fair market deal (15 for Zeke is fair), it might not be ideal, but for a truly elite player it's better to just get it over with instead of a doing a whole dog and pony show before eventually paying it anyway.