Let's recap:
HMS currently has no drivers that they developed. They did sign two rookies that other people developed and those rookies seem to have had some success.
SHR has no drivers that they developed.
RCR has one driver they developed in Austin Dillon. If we're saying Logano's performance at JGR was bad, Dillon's performance must also be ___.
Penske has no drivers that they developed. Similar to HMS, they did sign a rookie that someone else developed.
RFR has Biffle (success), Bayne (failure), and Stenhouse (failure).
MWR has no drivers that they developed.
JGR has Denny Hamlin, who has 25 wins and three top 3 finishes in the points standings.
CGR has Kyle Larson, who is likely to be a success but could easily become another Logano. We just don't know yet.
I mean, sure, JGR doesn't have a great success rate. But if JGR is bad, the rest of the Cup series is absolutely horrible right now. RFR had its successes in the past but quite a few failures as well. HMS has basically no drivers that were developed by HMS and then succeeded at HMS. You could give them credit for the likes of Kyle Busch & Brisn Vickers but then you need to give JGR credit for Logano's current performance. You can't really give HMS credit for signing guys developed else where (like Gordon & Johnson) because that's not driver development -- they just hired guys that other people got to the stage right below Cup. In the same way, JGR can't take credit for Stewart given they signed him as an IRL champion.
I really don't get the hate for JGR. They suck at driver development programs in terms of successful talent on their team but with Hamlin alone, they've done better than pretty much everyone other than RFR.