The report states the OCS-IS is the most costly because it robs peter to pay paul, taking usually senior NCOs out of units, and directing them to officer corps. It also takes them out of the Warrant pool, which pulls from senior NCO's. The report claims that OCS takes a NCO with 5-10+ years experience, takes him away from Soldiers, platoons, companies, etc... and puts him/her into OCS. After completion, they will serve as a 2LT, but then have to go to degree completion. Once back, many will be close to 20 year retirement, and many are eligible to retire before they make MAJ, which does not fill the mid-career officer shortage.

Years of service + OCS + branch training + degree = most costly. That's their metric.