IBM can manage the Apple hardware with so few people partially because only 5 percent of the user base calls the support desk. Compared to 40 percent of Windows users at IBM contacting the company's help desks, that's a vast difference in both required resources and costs.
Then there's the long-term value Previn thinks IBM will see by investing in Apple hardware. "A Mac still has value three or four years down the road," Previn noted at the JNUC.
Clearly, devices running Windows still have value too but perhaps not as much; I've routinely sold a few dozen computers over the past 20 years and find that Macs retain more value than their Windows counterparts. Granted, that's just a personal observation but if you've ever bought and sold a Mac -- or an an iPhone or iPad, for that matter -- you might have seen the same.
Obviously, IBM is now a formal partner with Apple in the enterprise; both for internal hardware deployments and in creating business-ready iOS applications. So I wouldn't expect Previn to wax poetic on any of the challenges or problems IBM is facing with Apple devices.
Even so, the support figures are staggering. The company can have a single I.T. admin for every 5,400 deployed Apple devices whereas Gartner suggests that if your enterprise has one support person for every 70 employees, you're doing well.