Good trainer, even very good, but not a great one like Bomac. That's an honest take, no hate. Derrick James is still learning imo.
Dude knows boxing, but doesn't talk as much about what the other guy was doing in the ring during the fight and rather still tries to teach/coach his current fighter - that's something you do before the fight or on the pads. When you say things like "you need to use more movement" rather than "They're doing this __, do __ next time" it's almost like you're not trying to break down the other fighter, but still coach up your current one. It's like you're playing as your boxer more and not playing against the other fighter if that makes any sense.
Yes, "keep your hands up" is good advice because the other boxer is punching your fighter in the face, but can you answer why and how the other fighter is having that kind of success?
Derrick James most times is like "Keep your focus", "don't fall for the feint", "walk him down", etc. and you absolutely can't bring that to a Terence Crawford match. Fighting someone like that you need an outside observer to help you see something you're not.
After they figure out what's happening, a great trainer/team knows how to give simple, effective advice not too detailed either because you don't want to confuse your fighter while there is so much stimuli and around that ring.
Bomac breaks down the other fighter in-between rounds. You're literally going up against a corner of boxing brilliance vs Crawford in addition to a multi-faceted prodigy in that ring who can think dynamically. Like watch that Gamboa fight during the 2nd round: Diéguez was telling Crawford "All he's is doing is trying to time you for the right hand, that's all they're doing. Keep moving back, they'll reach and you counter" or how Bomac during the in-fight interview said "Benavidez isn't catching that 2nd jab, we told Bud to double up more". They're paying attention to the other fighter's tendencies rather than telling their fighter to keep "Doing what you're doing, but do more of it".
Additionally, Floyd Sr. was really good at this. Floyd Sr. with Oscar would call out when he'd see the other fighter was gassed and time to go to the body or throw a combination or that the jab is working and to go back to it. Oscar would then go out there and execute. I still think we were robbed of some really high-level boxing if Floyd Sr. was Oscar's trainer vs Floyd Jr. It probably would've been the closest anyone got to beating Floyd and the most entertaining 24/7 by far. Not to mention that was the fight where Freddie Roach was able to get a close look at De La Hoya and know Pacquiao can make the jump. History-changing decision there by Oscar. That also goes to show how much Floyd Sr. and Oscar worked well together. Additionally, especially in the early 2000's when Floyd Sr. trained other fights like Francisco Bojado they mentioned how much of a no bullshyt trainer he was and actually a little too strict for some. Dude would teach pre-fight and analyze during the fight.
Edit regarding Floyd Sr: Hatton said Floyd Sr. overworked him too much. Floyd Jr. said Floyd Sr. was really strict as a trainer when they were younger. Apparently still trains fighters hard to this day, but has lightened up some. I think as Floyd Sr. got older and more spotlight (and a little more senile) people kind of underrate how good of a trainer he is and highly underrate how good he was as a trainer. Oscar wouldn't have kept him around for five years knowing his reputation to drop trainers (exceptional ones like Roberto Alcazar and Emmanuel Steward) if he didn't think he was an exceptional trainer. I say this because Derrick James immediately got spotlight as a trainer, but Bomac and Mayweather Sr. really took a long time to get the same spotlight.
