SEO rebranding question walkthrough

A broach niche domain acquires a specific domain and wants to 301 redirect it for branding purposes, what’s best practice?

Ex:

www.sports.com buys www.basketball.com
They redirect the basketball.com homepage to www.sports.com/basketball
And they do general redirects of all the basketball.com blog posts, so that www.basketball.com/best-basketball-players becomes www.sports.com/best-basketball-players

'basketball' tags are added to all basketball blog posts despite now being part of the new broader root domain

What happens next?
www.sports.com sees an immediate jump to all basketball related keyword rankings from www.sports.com/basketball page
But the keyword rankings/traffic for all the blog posts drop 10% after redirecting to sports.com and probably won't recover since the new domain is no longer a basketball authority website but a broader sports site.

The redirect strategy is spot on, but what will happen afterward is difficult to say. You may not see a fall, but in super-competitive niches there maybe a drop of 2 or 3 places.

The redirects will most likely boost sports.com's basketball section/articles but from basketball.com's perspective it might drop a little due to the fact that it's moving to a broader niche website.

As stated in the post above me your overall strategy is on point but remember to only redirect where it makes sense. A redirects will no matter how you tweak it tell Google that my former content is moved from here to there. If you have articles that don't match content on sports.com don't just redirect to the homepage, makes a new article and then redirect to that.

301 has great value if it's used properly as SEO is a marathon not a sprint.