Marshalls reports on small arms in Korea was sparkly compiled from interviews of many combat veterans.
Not a problem.
Starting in the seventies information began to come out about Marshall and his methodology. Some of it were from veterans that he interviewed. They stated that he led people to believe that he interviewed the vets days and sometimes even hours after the action when it turned out in many cases they interviews took place months later. Some of the men interviewed stated that Marshall had them providing details that they couldn't recall at the time of the interview.
In other words it began to appear the Marshall made stuff up.
The biggest problem arose with Marshall's assertion that his research revealed that only a very small number of troops actually fired their weapons in combat. At the time this was like a lightning bolt striking a tree. Caused the Army to revamp it's entire training program - which cost millions of dollars.
Then years later it comes out that there were some serious problems with Marshall's figures.
Now while some of it was probably the work of people who didn't like Marshall there were some problems. I suppose it could be argued that Marshall saw a problem and took it upon himself to fix it - so he inflated numbers and ommited other things. But it doesn't change the fact that there were problems and all of his research has to be looked at carefully now.
That's what I was referring to.