Funny because in one of my video interview I mention that a lot of people would misinterpret what I say and will make fun of me for saying that the eccentric portion of a lift is not important for growth.
IT'S NOT WHAT I SAID.
I also never said that eccentric-less training is more effective than regular lifting.
What I said was that the total amount of work you are doing is a very important variable when it comes to stimulating growth. But that if you try to pile on the volume while always emphasizing the eccentric, you risk creating too much trauma an neural stress to recover from in time for your next workout.
I DID mention that de-emphasizing the eccentric makes a movement LESS EFFECTIVE for maximum growth... but that it STILL STIMULATES SOME GROWTH.
So you perform your regular lifting THEN add volume by adding eccentric-less work.
However, except for some rare cases, I am against over-emphasizing the eccentric portion by going excessively slow. People claim that a slow eccentric creates more muscle damage. This is not the case, at least not in individuals with of an intermediate level or more.
See, the eccentric phase of a lift is FACILITATED by friction (intramuscular friction). And the more muscle mass you have and the more experience (more intramuscular scar tissue) the more friction you can create. During a slow eccentric, the friction takes over a greater proportion of the work, so in essence the muscle fibers do less work.
The eccentric might still FEEL harder, but it is mostly because of an hypoxic (lack of oxygen) state caused by the muscle's constant tension (blood cannot enter a contracted muscle, which leads to a lack of oxygen and an accumulation of waste products).
If you believe in the "fiber tearing theory" then a purposefully slow eccentric is NOT the best way to do a rep as it will actually cause LESS muscle tear.
To cause maximum muscle tear you must CONTROL the weight during the eccentric without going slow.
That's not to say that slow eccentrics don't have their place... they do, if you goal is to create an hypoxic state in the muscle and an accumulation of waste products. This, in itself, can stimulate growth via hormonal factors. But it is wrong to believe that it is due to more fiber damage.