The evil of Presidential candidate selection in the modern era, is the mix of party politics with direct voter primaries. It should be one way or the other, but not a mix. That's the way the Founding Fathers intended.
If every state stuck to direct primary elections, as some have come to think of the selection process, then there would be no need for the party convention antics. If the parties are truly concerned about how "their" candidate is selected, then they wouldn't allow these open primaries. They can't have it both ways and expect civility in the process.
In either case, the GOP is a dead party. It has become too broad and no longer has a political identity. The DemRats have their liberal progressive identity. The Constutution Party has its identity of following the constitution. What has the GOP got? Who do they identify with? Their brand doesn't exist excep as the party of Trump, McConnell and Ryan. Wow, now that says a lot. NOT!