Meaning of "if anything" [closed]

Mr. Shue believes Sugar Mota adds value to the team, increasing their chances of winning the nationals. Rachel seems to disagree with the teacher's decision to recruit Sugar Mota. Rachel does not share the same confidence in Sugar Mota as their teacher does. In this instance, "if anything" is Rachel's way of saying with all the possible outcomes adding the new member to the team may create, the most likely outcome is they will lose the competition with the new team member. You were on the right track with regard to "if anything happens." In this case "anything" can be either good, or bad. Rachel is suggesting the latter is more probable.

"If anything" means if anything significant happens. The only alternative is for nothing significant to happen. So "if anything" means "the only alternative to nothing of importance or significance".

"If anything, she is gonna kill all of our chances to achieve that elusive goal (she means nationals by that)."

This means that either she will kill their chances, or she will do nothing relevant. That means she will definitely not help them. If she has any effect whatsoever, it will be to kill their chances.