Even in the cases you cite "flooded" is being used to mean "far too many" and therefore has a negative. It's not too hard to imagine that someone saying "far too many black players" has a problem with there being so many black players. Why should it matter? Why are there "far too many"?
The argument I've been making earlier is that the ideal situation is when no-one cares what race, gender and so on managers, or MPs, or anyone has. That means if it's all white no-one raises an eyebrow because we know they got there on merit, and it means also that if we have lots of black footballers that's because they are very good footballers. To imply that it's a "flood" is a pretty clear-cut case of wanting there to be fewer, and with no particular reason provided why it should be "far too many" it's difficult to avoid thinking of someone who says that as racist. I would object just as strongly to the idea of something being "flooded with white players".