I don’t want to create an argument in this thread, so this is all I will say on that. If you look at his many writings, especially on speed enhancement, you will see the use of squat as a primary resistance exercise, not isometrics. Isometrics can very well be added in addition to the program, but he doesn’t go out of his way to advise them.
Most everyone who has gotten addicted to isometrics for speed improvement has gone no where, as is evident by the many journals on forums around the net, including the inno sport forum. Sure they are good in theory, but the basics are for more effective. That being said there’s no reason to not experiment with them IN ADDITION to a sensible isotonic resistance training program.
Tendons strengthen significantly through sprinting/various jumps, leaps, and bounds. Dynamic resistance training would also, considering REA Squat, REA Lunge etc is included in that category.
IMO, regardless of what resistance training ideology you follow, it has to make you maximally stronger over time, if it’s squat or iso lunge, it shouldn’t matter too much but i’d give the edge to squat 
The most important aspect of lifting to aid in speed/vert improvement, imo, is the delayed stimulation from the session and how it effects subsequent speed/power sessions. This can be done with isometric or isotonic lifting, but i’ve only used exercises such as barbell squat & barbell lunge due to their success throughout history. When I’m out of my GPP phase, the most effective form of stim i’ve ever used comes from Verkhoshansky’s Maximal Strength Effort Methods; High intensity squatting with rest between reps (2-3x2-4 90+%). Nothing comes close to providing as much potentiation as this simple method, IMO. I’ve used it for same-day stim, next-day stim (1-3 days), in season strength maintenance with very low fatigue, and a quick peaking method consisting of high frequency MSEM (multiple sessions in a row) + very small deload.
My point in all of that, is that even though Verkhoshansky makes isometrics seem very alluring, if you read all of his forum posts, he really sticks to the basics and to his system. If you were to utilize isometrics, he would probably advise you use them in block A.
Sorry for possibly derailing.
R.I.P.