I don't know why you would use TDs to determine his value.
Because they count for 6 points?
It's data, the sample size is sufficient, and the usage/utilization in the RZ has been consistent. After 5 years you can't keep saying "TDs are variable." Same deal with Diggs, great route runner, PPR pinball machine, but he doesn't score. Different reasons (burner speed, size for jump balls & fades) but the point is TDs are a heck of a lot more predictable than people think they are. Week to week, of course now. Over time, it is not a volatile stat IMO based on other research I've done. I could be wrong and I know I'm outside the consensus opinion "TDs are variable", but I believe independent thinking has served me well.
TEs with more RZ catches than Ertz:
2017 - Clay, Fleener, Rudolph, Witten*
2016 - Bennett, Brate, Clay, Doyle, Fleener, Gates, Henry, James, Kelce, Olsen, Pitta, Reed, Rudolph, Tamme, Witten**
2015 - Allen, Barnidge, Bennett, Cameron, Carrier, B. Celek, G. Celek, Chandler, Davis, Daniels, Dickson, Donnell, Ebron, Eifert, Fleener, Gates, Gilmore, Green, Gronk, Hardy, Hoomanawanui, Kelce, Olsen, McDonald, Miller, Reece, Reed, Rodgers, Rudolph, Thomas, Walker, Watson, Whalen, Witten
2013 & 2014 - Happy to do these if you like but I think you get the picture. Some pretty mediocre talent on the above lists. BTW, I probably missed a few, I did this by eyeballing RZ target lists that weren't filtered so I probably missed several.
Another metric: % of RZ targets. Ertz was is 28th this year, 15th a year ago amongst TEs.
Prefer targets over receptions? Number of TEs with more targets 2013-2017:
2017 - 6 (1 TD)
2016 - 15 (4 TD)
2015 - 18 (2 TD)
2014 - 8 (3 TD)
2013 - 37 (4 TD)
Mercedes Lewis catching three TDs is variable, unsustainable, unrepeatable. Zack Ertz finishing a season with 4 TDs or less has been a fact four years.
Maybe this year is different.
Anyway, he's a good TE. I just don't view him as elite, and he has never been a guy I targeted (actually I consciously avoid him.) More Ertz shares for everyone else, it's all good.