Clinton's weekend get-out-the-vote rally with Pascrell certainly didn't hurt, but in the end, the ex-president was in the Garden State for just a few hours, speaking to citizens already energized enough to turn out for a campaign rally. The time and money Pascrell's campaign put into identifying, canvassing, and turning out his voters was a far more powerful force than Clinton's imprimatur.
Same goes for Critz in Pennsylvania's 12th District. Critz and union allies boosted turnout in his section of the seat far beyond its share of the district-wide population. The campaign and its friends used Clinton's support to rally voters, but it wasn't their principle thrust against Rep. Jason Altmire.
On the flip side, Clinton made a trip to El Paso, Texas in support of Reyes that was very similar to his recent pro-Pascrell stop in New Jersey. The difference is that Reyes didn't run a great campaign, while Democratic nominee Beto O'Rourke personally introduced himself to thousands of voters during an energetic primary run that included some high-tech voter targeting. And Chavez, in New Mexico, couldn't survive sustained attacks on his record and character when he was a frontrunner months ago.
Ultimately, a gold-plated endorsement like Clinton's is a great driver of media attention. But it's a complement, not a substitute, for the things that really make an effective primary campaign.