I've no inside knowledge on Google, so can't comment on the rationale for selecting those being let go. From the outside though, Google under Pichai increasingly looks like Microsoft under Ballmer in the late 2000s/early 2010s. Balmer was lauded for delivering good numbers from a dominant market position. That was fine - until it wasn't. Under his watch, Microsoft completely misjudged the internet and totally missed…
One difference with the previous leadership is how little decisive strategic action is going on. Google founders leaned hard on the company to steer it and "bet the farm" in clear areas. Pichai doesn't seem to.