what is the "dead" value? and does it matter?

hopefully a simple question to explain with rather easy answer....maybe

I'm in a few different pools...various types, sizes and different coins too.. and looking at various stats that are available to any registered user/miner and one of the indicators puzzles me...

the "dead" value..

in the pool stats section.. got "Total Mean"..as in the overall total average pool hashrate..in mean MH/s and area for that ...what is the area anyways? (ie 20.9TH and 2540GH, etc...)..always wondered but never sure..dont care much about that but if you have simple answer..sure
..then there are the "Orphaned" stats - once again in total MH/s hashrate and then the area too... and then "DOA"...shows a mean and area too..

can you quickly confirm/explain this Dead On Arrival stat? and curious if this is the same as the Dead value I'm about to get to.. those are blocks/units sent to your miner that are unworkable as soon as they get to you...?

anyways.. the stats go on and on..but then the two or three key stats that are under the INDIVIDUAL MINER STATS. (hashrates and payouts per trans)

Have a graph and value to show my current hash rate per second...and my average...and has a graph line for it..in this case..a blue line...and then the other value is simply "Dead mean" and area... and the dead mean is given in a MH/s value too.. with a RED graph line... what is this exactly?
I don't believe it's the "rejects" in local miner stats from my pc..numbers dont add up.. nor do they with DOA's ..i think.. and I don't think it's affecting my bottom line..but I really have no clue.. but it's basically either ALL or NOTHING...and what I mean by that is its basically in line with my Hash Rate graph line.. but a different hashrate number or it's roaming around the bottom way below my hash rate line.. throughout any given day...every few hours...it's right up all the way...and then a few hours...around the bottom with very low value.. now my payouts and value per transaction numbers are not in any way changing with this so curious what this number means and if it's matters and is there anything to do about it?

Thanks!