I agree, but I don't think you are playing perfectly.
Did you do 10 games in 4 hours? Slow down the pace to be more careful. Timing volleys, power management, and keeping track of systems and crew has me pausing the game often.
What's the first thing you do when you run into the boss ship? I send a boarding party to take out his missile launcher, a pair of Mantis are nice. Another party takes out his ion weapons next. His weapons are separate from the rest of the ship making taking them out with boarders easy. Once both of them are down, the boss isn't much of a threat in stage one. Take out the Beams next, and that just leave him firing three lasers, no problem if you have at least 3 shields. Now leave that one guy on lasers alive. The weapons left to right are Ion, Laser, Missile, Beam.
Now that you have taken out 3 out of 4 of his weapons and the crewmen manning 3 of them, time to work on the rest of the crew. If you kill everyone but the one guy in the laser, stage 2 and 3 will go easier. You need a weapon that is good at creating fires or breaches, a bio beam might also work, or a healing bomb for your boarders to take them out. Fire bombs and Rockmen are a good combination. Make sure his med bay is down. Damage gets fixed, but dead crew members are gone for good. Leave that one guy at the laser to keep the ship from going automated. A hull repair drone is nice to have in storage if you don't regularly use one, to fix damage between stages.
Stage 2 With no one in the main body of the ship, and 3 out of the 4 weapons unmanned, your boarders will have an easy time of it now. He uses a defense drone, so if you have a single missile launcher it will be almost useless. Either have several or don't use any at this stage. So it's useful to have an extra weapon in storage. Also you don't want to use fully energized stealth in stage 2, it will last too long, and a second power surge will happen before your steal is recharged. Don't use it too soon; timing is important. You can even get by with one unit in stealth. Save it till your shields are down, and then go stealth before you take any damage; a benefit is that by only using a single charge in stealth is that it will be recharged faster, and almost always ready for a second wave.
Stage 3, he sends over all his crew to board you. If you killed off all his crewmen but one guy in stage one, that part will go easy. Power surges are shorter so you only need one unit of stealth, just wait till you actually see it coming to hit stealth mode.
Also as soon as shields are damaged or frozen with an Ion attack, move that extra energy to engines for better dodge. And back again when they are fixed.