Last year in Double-A Jackson, Tyler O’Neill’s bat started off hot and cooled down slightly over the second half of the season. This year, so far, it’s the opposite: in the first half, O’Neill slashed .236/.323/.447; in the second half, that’s up to .321/.367/.679.

Updated numbers on the Tyler O'Neill Tear: last 25 games, 330/432/723 with 11 HR, 25 RBI. This has come over 94 ABs with 16 walks and 31 K's — Mike Curto (@CurtoWorld) July 19, 2017

The K number is concerning; as the power comes back into his bat, so do the strikeouts. Overall, O’Neill’s line on the season currently sits at .243/.326/.466 with a 28% K rate, which is not going to light up any GM’s eyes. That is, unless you look past the stat line to what he’s been doing lately:

Love a good "outfielder doesn't even turn around" homer. pic.twitter.com/37ZV1RN3fm — Brett Gleason (@brett_gleason) July 19, 2017

Or perhaps you’d prefer something a little more opposite field?

O’Neill’s .223 ISO is his highest mark since he played in the hitter-friendly California League and put up a bizzonkers .297; he also walked 6.5% of the time while striking out at a clip of 30.5% (ah for the halcyon Jack Z years). That he’s managed to put up such a number while maintaining his plate discipline numbers from last year speaks to O’Neill’s development as a hitter. The fact that this power has come with a recent strikeout spike is something to watch, but at just 22, O’Neill has plenty of time to put it all together.

There’s another aspect to O’Neill’s game that tends to be underrated, and it’s his excellent speed. For such a burly man, O’Neill is quick and compact on the bases, and is able to explode out of the box quickly. He’s smart on the basepaths and was 9/11 in stolen base chances in the first half (last year he was 10/12 for the season, so he’s on pace to best his 2016 SB total by the end of the month). He’s also able to use his excellent closing speed in the outfield:

But for all the talk of O’Neill’s slugging, not much is said about his outfield defense, even as he had a fairly dramatic showing in the AFL All-Stars Game this past fall.

It’s natural, for a club that doesn’t have pitching and has an excess of young, controllable outfielders, for Tyler O’Neill’s name to come up most often in trade rumors. We saw that last year, when O’Neill was pulled from a game after being HBP and Twitter promptly freaked out. But as much fun as it is for some to dream on a Tyler O’Neill trade, the reality is it isn’t a very good idea, for the following reasons:

As outlined above, O’Neill is a toolsy player whose speed and defense aren’t widely known selling points and whose numbers are currently depressed as he adjusts to Triple-A pitching. Selling him now is selling him at the nadir of his value, unless you believe Tyler O’Neill will not get better than what he is now. Nothing is certain, but looking at his peripherals, as I did in this piece in June, O’Neill has run into some poor BABIP luck early in the year but is largely maintaining his same batted ball profile and plate discipline numbers from last year. The power surge is exciting, but comes with an inflated K%. All of these factors combine to artificially depress O’Neill’s price—and, as the lone remaining MLB-close, shiny trade piece in the Mariners’ system, O’Neill may have more value to Seattle than he would have to others.

The trade for J.D. Martinez told us what a veteran corner outfielder is worth, and it’s not much. In return for J.D. Martinez, the Diamondbacks gave the Tigers Dawel Lugo, currently on his second tour of Double-A and performing a little worse than he did the first time (and who has never recorded a BB% above 6%), Sergio Alcantara, an A-level, light-hitting shortstop who’s repeated levels multiple times since being signed in 2013; and Jose King, who probably has the highest ceiling but is 18 and currently running a K% near 50% in rookie ball. Clearly it’s a different situation dealing with O’Neill, who is a building block for the future rather than a rent-a-player, but the trade suggests the value of outfielders isn’t anywhere close to the value pitching has, which is concerning because:

Right now, the Mariners need pitching. They need arms, arms, and more arms. Unfortunately, so does everyone else. Flipping Tyler O’Neill for a young, controllable starting pitcher sounds fantastic, doesn’t it? But after the Quintana trade, the price for elite young starting pitching was set, and it was set high. Tyler O’Neill and Friends will not bring back Chad Kuhl, or Julio Teheran, or Jeff Samardzija, if Jerry suddenly decided he didn’t care about paying people all the money. In order to get David Phelps, a reliever who has been worth .3 fWAR this season, the Mariners had to send exciting young outfielder Brayan Hernandez and three pitchers (dependable but unexciting fifth-starter-type Brandon Miller, and two volatile but with flashes of potential arms in Lukas Schiraldi and Pablo Lopez) to help the Marlins build up their farm. I’m just not sure we see a return in value commensurate with O’Neill’s skill set in this current market.

Trading Tyler O’Neill would suck, because he’s fun to watch, especially right now. Literally while I was typing this he had a two-run home run game for Tacoma, lifting the Rainiers to victory. If the Mariners got back a controllable, MLB-close starting pitcher who could help the team in 2018, it would make losing the most exciting prospect currently playing in the system bearable. But O’Neill’s depressed numbers, plus the feedback from the current trade market, suggest this isn’t the best time to move him. Sacrificing O’Neill for an outside chance at the wild card with a subpar pitching staff isn’t the best thing for the team, nor its fans.