The organization I work for outsources technical work. The contract with the vendor included increased payments as they built experience in our applications. Some years into the contract when we asked for details of who was working on the contract, the only resources with more than 2 years experience were the 3 resources we insisted stay on site - they had been in place for 5 years and were very knowledgeable. We were paying for a constant training cycle for the churn of the other employees and this was often reflected in the quality of response and code. This situation would have been a nightmare without the long-term employees acting as mentors/senior consultants.
If IBM is going to cycle everyone every two years, their clients should ask for a discount as the quality of support is about to decrease. IBM should consider some long-term support roles in support of the "churn" whether that is due to the industry or their own HR mandates.