Does '几个运动员应该尽到自己的努力了，' have a critical tone in this sentence?
“几个运动员应该尽到自己的努力了” here is to add an reason/excuse before saying the bad result (但是有个别项目，个别人出现了问题。). 

I think the author feel sorry to say the bad result, so he put an positive thing and praise our 运动员 first before addressing the bad result. 

In English, there is a phrase “not to rain on your parade”. I think they are the same kind of idea.