Comment by cratermoon

I worked at a company that had a Rails monolith that underwent similar scenario. A new director of engineering brought in a half dozen or of his friends from his previous employer to write Scala. They formed up a clique and decide Things Were Going to Change. Some 18 months and 3 projects later, nothing they worked on was in production. Meanwhile the developer that was quietly doing ongoing maintenance on the monolith had gradually broken out some key performance-critical elements into Scala and migrated away from the Ruby code for those features. Not only had it gone into production, it made maintenance far easier.