What kind of broadhead did you lose that deer with? Mechanical or fixed blade? If is was a fixed blade, does that mean all fixed blades are bad?
Look there are good and bad broadheads out there, both fixed and mechanical. There are good and bad shots. Make a good shot with a good broadhead, and you'll probably have a short, easy tracking job. Make a good shot with a bad broadhead, and you'll probably still find the deer though you might have to work a little harder. Make a bad shot with any broadhead, good or bad, and you're in trouble.
Like I said, I don't think the Tekan is a good head. I only have shot one deer with one, but I didn't like what I found. I got a pass through, but one of the blades was broken off, the wound wasn't impressive, and I didn't have a good blood trail. It was very much like the original poster's experience. But to say all mechanicals are junk because of one head or one experience is stupid.
I haven't killed as many with my bow as a lot on here. But I've tried a lot of different broadheads, and I've settled on a rear deploying two blade broadhead. I seem to get much more gaping wounds, better bloodtrails, and shorter tracking jobs than with fixed blades. Again, it's more about shot placement than anything. This constant arguing over broadheads is stupid. Use what you like and what works for you.
But, one experience with one brand of broadhead isn't enough of a sample size to say that all mechnicals are bad. For the record, I've lost more deer with fixed blade heads (3) than with mechnical heads (2). (Of those, at least two lived until they were killed in gun season. But this has more to do with experience than it does with the broadhead.
And the argument that you don't want any moving parts isn't very consistent, considering that many people are shooting delicate multiple pin fiber optic sights, some even moving pendulum or floating pin sights, with drop away or otherwise "moving" rests, out of modern compound bows that have complex cams and "moving" parts using a mechanical release. If what you really wanted was the simplest weapon with the least moving parts to break, you'd be using a spear, or at least shooting a recurve instinctively, because it has no parts to break other than the bow and the string. But most people aren't. So, there lies the inconsistency. People are using the most modern bows, sights, and rests regardless of how complex they are or how many parts there are to break and screws there are to back out. But many of those same people will argue that shooting mechnical broadhead is bad because there is too much to break. Just doesn't make sense.