The general opinion appears to be less that it's a good or bad trade for the Diamondbacks, and more that it isn't a very good one for the Mariners, because it doesn't address their problem. For example, according to David Schoenfield of ESPN, "The problem is they don't have hitters, they don't have enough guys who can get on base, they haven't developed hitting prospects... Trumbo is hitting .259 with a .299 on-base percentage. He has a career .298 on-base percentage. This is not a solution."
Jeff Sullivan, Fangraphs. "The optimist would say the Diamondbacks are buying low, but it does feel like a bit of a light return. Trumbo’s a marketable piece, even with his limitations. But there are two things: one, the Diamondbacks were running out of time to clear room, and two, ultimately, this is what the market offered. A Mark Trumbo trade isn’t a blockbuster trade, not within the industry. It’s a trade of a guy who hits right-handed dingers. Maybe, one day, Gabby Guerrero will be hitting right-handed dingers. Maybe he’ll hit more of them."
Steve Adams, MLB Trade Rumors. "Castillo is a career .250/.316/.392 hitter that posted a combined 105 OPS+ from 2012-13 before taking a step back in 2014. All told, his bat has been about five percent below the league average over the course of his career, which is solid offensive output from a catcher... Leone is a reclamation project for the Diamondbacks, but if he can return to anything close to his 2014 output, he’d be one of the most effective pieces in Arizona’s relief corps... Guerrero has baseball in his genes and is a high-risk, high-reward type of prospect... he could ultimately be an everyday right fielder, but the likelihood isn’t great without adjustments to his approach."
Ken Rosenthal, FOX Sports. "Trumbo was an obvious trade candidate, and the D-backs’ need for a catcher due to the season-ending loss of Tuffy Gosewisch further motivated this deal. But three days ago, when I asked D-backs general manager Dave Stewart about Trumbo, he acted as if I wanted to know whether he would trade his firstborn child. Stewart only has been on the job since last September, but I’ve got to hand it to him. His response was classic GM-speak, well-crafted subterfuge. Heck, Stew probably had the deal half-done as we spoke."
Chris Towers, CBS Sports. "At some point, it seems clear the team will need to make another move, but the status quo remains in the outfield for now. The package the Diamondbacks received for Trumbo and Nuno isn't super enticing, especially when it comes to immediate impact options. The catching-starved Diamondbacks could certainly use some help there, and that might be the part of this trade that returns the most immediate dividends... But the main draws in this deal are the minor leaguers, chiefly Gabby Guerrero... thanks to his solid defensive potential and the pop in his bat. However, the 21-year-old has always had a lot of swing-and-miss to his game."
Mark Townsend, Yahoo! "Not exactly a notable return, though Arizona finally gets the catching depth they've needed since trading to the Cubs. All things considered, it's a pretty bold move for early June for both sides... One has to wonder if they could have acquired a more impactful prospect or two closer to the deadline. The two prospects in the deal — Reinheimer and Guerrero — are not rated among baseball's Top 100 and there's very little buzz surrounding them aside from the fact that Guerrero is the nephew of long-time major leaguer Vladimir Guerrero. Great bloodline, but that won't necessarily translate to a breakout."
Ian Sullivan, Rant Sports. "What’s more important about this trade for Arizona is that it opens up the team defensively. With Jake Lamb nearing his return from the DL, the move allows the young infielder to maintain his position at the hot corner. .. This move also clears what would have been an extremely logjammed outfield, allowing the team to consistently play Ender Inciarte and A.J. Pollock, whose talents cover all aspects of the game. It’s clear that the Diamondbacks have accepted their needs to rebuild, and they are going about it the right way. The offensive and defensive parts of the puzzle are fitting together for Tony La Russa and his team."
And finally, always fun to go over to our sibling site, and see what the taken on the deal is from the other side of fandom. Scott Weber of Lookout Landing writes: "It'd be nice to get excited about a trade like this. After all, the offense has been terrible, the rotation is banged up, and these two players do fill needs. But after a series of Mariner games that just felt so exhaustingly Mariners, this trade feels the same. Exhausting. It embodies everything about this current front office that hasn't worked over the past several years, and yet here we are, trying it again...The 2015 Mariners, face down in the middle of the chosen year, and an answer to adversity is doubling down on a tactic that's never worked, at a time that comes far too early."