For more control over incompetent migrations (see example complaints in posts tagged migration-rejection), would it make sense to try a new kind review? I would call it
suggested migrations queue
Located at target site, it would contain a list of questions flagged / voted for migration. Target site users with appropriate privileges (eg close voters, or editors etc...) could submit their feedback on whether the proposed question is a good fit for migration.
Source sites could use the feedback provided through this review queue when questions are closed.
In particular, it would be interesting to try this as a remedy against the glitch of current review system referred to in another question as Bandwagon effect in close votes:
...people are agreeing with existing close votes without thoroughly evaluating whether they're accurate.
'Migration review queue' idea has been introduced here:
...Have users on the other site check through migrated posts before they get integrated into the site they are migrated to. We should know what belongs to our own site, don't we?
This idea is similar to one proposed in Add review queue for recent migrations with the difference being that review would be performed prior to migration, not after it. It is also similar to proposal about Accept Migration voting mechanism for migrated questions with the difference being that review doesn't block: migration gets rejected only if target site reviewers were fast enough to counter-vote.