The other guy, before Nelson, was William Knudsen, a specialist that came out of heavy manufacturing, primarily in the automobile industry. I think he headed OPM until Roosevelt replaced it with the War Production Board (there's a bit of overlap there). I've read a lot about these two guys, both generating quite a bit of controversy. Knudsen was, in my opinion, a nuts-n-bolts process guy who was able to work with the various industries and corporate leaders to ramp up production, or at least lay the groundwork for them to ramp up production. His problem was that he had little in the way of political chops; he was fundamentally an engineer and seemed to struggle to get folks to do things when they didn't directly work for him. Nelson, a chemical engineer and former high-ranking corporate executive, had the people skills and some fundamental technical knowledge. By the time they created WPB, Nelsen would have a few thousand folks working for him (Knudsen, who had a relatively small staff, had largely been a one-man band).That's the guy and he never received the thanks he was due IMHO. How do you thank the architect of victory properly?
WMC
One clarification of what I posted earlier - neither Nelson or Eastman made it to the end of the war. Eastman died, Nelson they ran off. After close to three years of standing on the hill whilst holding the lightning rod, Nelson was replaced by Roosevelt in 1944, the level of criticism of Nelson's decision-making and prioritization assignments growing to epic levels. Numerous contemporary historians pile onto Nelson based on, IMHO, the criticism he received from the military and civilian sectors at the time. His reputation has been considerably tarnished over the years by folks that fail to consider the massive political challenges of the task at hand (the things D. K. Goodwin wrote about him are just outrageous). It should be noted that they run rough-shod over his replacement as well. I think the production records and ultimate Allied victory speak volumes.
Eastman's health just finally gave out. He'd been at war for close to twenty years, first as head of the ICC from the late-1920s, through the Depression, and then into the years just before the war. As head of the ICC, his task had been one largely of managing the framework within which the American rail network operated. It was a never-ending dog-fight of corporate consolidation, rate-setting, labor/union battles, and safety regulation enforcement, all in a fundamentally unhealthy, uncooperative industry. Compared to Nelson, I think that made him better able to head the ODT and all of the political baggage, but by '44 he was just spent.