Mainframe modernization failures rarely come down to technology choice. Re-host, re-platform, refactor, rewrite — all four can succeed and all four can fail. What separates them is execution discipline and the ability to deliver value continuously.
The successful programs we've seen share three traits: they decompose the work into small, observable pieces; they pair domain experts with cloud engineers throughout; and they ruthlessly avoid big-bang cutovers.
The failed ones almost always tried to do too much at once, treated COBOL developers as obstacles instead of assets, and let architectural purity outweigh delivery momentum.