Sins of the Wreckers #4 is out on April 27th. And #5 is out on May 4th. Thanks to a call to my local comic store a week or so ago.
There is absolutely no chance that #5 will come out on May 4th. IDW always staggers releases so two consecutive issues are NEVER released on consecutive weeks. I think there was a 2 week window once, but it is typically 3-4 weeks at best. With the delays in the series due to Roche's personal life, I would expect end of May at the earliest. (He was just posting on Twitter a week or so ago about drawing #5.) Diamond either hasn't updated their listing and/or IDW hasn't given Diamond the most recent estimate.
I am just repeating the information that my local comic store gave me. That is the release date that they have for it.
If Sins goes down like LSotW there'll be another delay while you mix more of the pink-ish-purpley color.
Read the preview for sins. All the profanities. And that is merely the first five pages of #4. Slag slag slag.
For the record, no one can describe Prowl better than Larry David (referring to what he refers to himself in his latest SNL monologue):
I believe that Nich Roche stated on Twitter that he had some personal things he had to attend to and thanked IDW for giving him the time off between issues.