The Eve Fitting Tool (EFT) is a great way to identify whether a fitting you want to use will actually work, and tweak that fitting to your purposes. That said, you need to keep in mind certain limitations of the summary window to the right of your fitting. For example, EFT consistently over-estimates the amount of damage you can take.
Look at any kill mail, and plug that fitting into EFT. For the sake of argument, let’s use the “All Level V” skill option. The kill mail probably reflects about 1/3 the damage EFT says you should take. That’s because EFT lists “effective hp”, which modifies your damage by your ship’s shield and armor resistances. The only damage that matters is the kind that shows up in your Eve client in little red numbers in the center of your screen. It doesn’t matter if you have 53,000 ehp… if you’re taking 500 damage, that’s 500 damage off your shields or armor.
Also, keep in mind that EFT's summary about your tank makes no reference to repair modules… you need to calculate the total effect of an active tank yourself. And that 500 shield every 5 seconds will do you much more good if you’re facing a single opponent than it will if you’re facing many.
But another area EFT fails at is DPS. The DPS numbers you see are within optimal range. Tell me… how many opponents are going to fight a Gallente ship point-blank and let you get your full DPS on them? If you fly a Minmatar ship, you’re probably fighting in falloff range (if you’re doing it right), which cuts your DPS down to between ¾ and ½.
It’s tempting to think that a Hurricane gets 717 dps with drones, and think you can go toe-to-toe with anything out there. But about 100 dps of that is drone damage, which is delayed and subject to being destroyed, and the rest is subject to falloff penalties. Your real DPS may be around 400-450.
And we haven’t even gotten to tracking yet. If your guns can’t track a target, you won’t apply any damage whatsoever. If your missiles can’t track, the damage they apply will be seriously reduced.
But that’s a subject for another post. Just don’t go thinking that EFT’s stats are gospel truth. If you do, you’ll be in for a harsh reality.