One example last night was on the finale, masses of horde and shacked up in a confined area. I got smokered/pounced in very short succession (I believe I was the prime target due to my lower health) as the rest of the group were moving.
Because I was unable to let them know what was happening, they assumed I'd not heard the command to start moving.. which could start ****ing people off after a while.
Its not that they would not be able to see I was being targeted, but because of the difficulty in that situation a verbal warning from me would have shaved those few seconds off that could have got the area cleared and kept me up.. or not made me look like I was afk or not paying attention.
And yes, it was me that got boomer-ed out of the open window plummeting to me death (another thing I could not let them know about quickly enough)
I know its only small things, your probably a lot better at the game than I as v.s. is something quite new to me, but I honestly felt like I was definitely the weak link in the team because of not being able to communicate correctly.
) and in the chaos of battle (and the blur of boomer bile), sometimes a verbal warning makes things a lot easier. 
