Diamondbacks monthly mailbag: Trade deadline targets, best advanced baseball stats and more

From the moment I went full time on the Diamondbacks beat last summer, I had plans to do a written monthly mailbag.

Heck, Craig Morgan does it. It must be cool.

For a variety of reasons — primarily the fact that we already answer questions every week on our Mailbag Monday podcast episode — those plans did not materialize until now.

My hope is that this mailbag will create space for deeper analysis, more polished discourse and more exclusive content for you, our diehards, who are so incredibly important to what we do.

This first mailbag was a fun one. We’ll discuss everything from baseball road trips to Diamondbacks trade deadline targets to moving Ketel Marte to third base.

Without further ado, let’s jump in.

From Discord

Underrated stat: Barrel rate

Barrel rate has quickly become one of the first things I check when visiting a player page on Baseball Savant. It is more predictive of future power than other common power metrics like average exit velocity, hard-hit rate, etc. It also stabilizes fairly early in the season, meaning you do not need a full year of data for it be meaningful.

Overrated stat: Average exit velocity

I am not unequivocally opposed to average exit velocity, but it is important to understand how this stat works.

Say a hitter has three batted balls with exit velocities of 106.3 mph, 95.2 mph and 33.8 mph (that last one being a bunt up the third base line). This hitter would have an average exit velocity of 78.1 mph, which is terrible — even though they had two hard-hit balls and a potentially productive bunt.

Statistically, any time you average numbers that have such high variance — exit velocities can be as low as the 20s and as high as the 120s — there is going to be a lot of noise.

Casual consumers often make the assumption that high average exit velocity is necessary for success. Tell that to the man who’s been flirting with a .400 batting average all year, Luis Arraez. His average exit velocity ranks in just the 34th percentile and his hard-hit rate ranks in the first percentile.

All that said, average exit velocity does have value. It just needs context.

Am I allowed to take two pitches from the same guy? Give me Randy Johnson’s fastball-slider combo, and I have all the weapons I need!

To keep it simple, I’ll just stick to starting pitchers. I’m not sure exactly what criteria you had in mind, but here are five guys who could be good fits for Arizona:

1. Lucas Giolito, RHP (Chicago White Sox)
2. Jordan Montgomery, LHP (St. Louis Cardinals)
3. Jesús Luzardo, LHP (Miami Marlins)
4. James Paxton, LHP (Boston Red Sox)
5. Drew Smyly LHP (Chicago Cubs)

The Chicago White Sox have not played well, and they should probably sell. It would do the market — and therefore the D-backs — a big favor if they did.

Lucas Giolito is slated for free agency at the end of the year, and he has had a nice season. He is 6-5 with a 3.53 ERA, 1.18 WHIP, 9.8 K/9 and 2.6 BB/9.

Giolito’s peripherals suggest he is more of a mid-four ERA pitcher than a mid-three ERA pitcher — the long ball has been particularly problematic — but he is both good enough to move the needle for the D-backs while also not being so good that, say, Jordan Lawlar would have to be included in a potential deal.

With both Zac Gallen and Merrill Kelly being right-handed, it stands to reason that the D-backs might prefer to add a lefty at the deadline. Jordan Montgomery of the St. Louis Cardinals would be a decent option. He is on his second straight year posting a mid-three ERA, and he has the peripherals to back it up. Like Giolito, he will be a free agent at the end of the year.

Other lefties of interest include Drew Smyly of the Chicago Cubs and James Paxton of the Boston Red Sox. Paxton is the more significant of the upgrade of the two, boasting a 2.70 ERA, 0.96 WHIP, 11 K/9 and 2.3 BB/9 in nine starts this year. Durability down the stretch could be a concern, but Paxton’s fastball is averaging 95.8 mph this year, his highest mark since 2017.

We end with Miami Marlins lefty Jesús Luzardo, who is under team control through the end of the 2026 season. He is 6-5 this year with a 3.53 ERA, 1.15 WHIP, 10.4 K/9 and 2.2 BB/9.

Lúzardo would cost significantly more than anyone else on this list, but Diamondbacks general manager Mike Hazen might prefer to spend more on an arm that would stick around for a while than overpay for a two-month rental.

Plus, the last time Hazen acquired a controllable starter from the Marlins, it went alright…

From Twitter

We start with the usual: batting average, on-base percentage and slugging percentage. As much as the triple slash seems to be going out of style, I am still a big proponent.

Frankly, neither wRC+ nor wOBA are all that much better than OPS. Neither wRC+ nor wOBA are necessary — and, frankly, it would be tough to explain wRC+ to every baseball fan in the universe. Instead of pure OPS, though, I am going to take its park-adjusted and era-adjusted neighbor, OPS+.

We also need a way of measuring how hard guys are hitting the ball. I already spoke about the importance of barrel rate. We’ll grab that one, along with hard-hit rate.

Switching over to pitching, I would start with ERA (yep, just plain ‘ol ERA), WHIP and FIP. I know people don’t care as much about ERA as they used to, but come on, are we really going to introduce relievers by talking about their FIP from this point forward? ERA is a necessity.

That said, as with OPS, I think it is important to have the ability to adjust for the pitching environment. In addition to ERA, we will also need ERA+.

We also need to measure how often pitchers strike out and walk opposing hitters. We’ll take strikeout rate and walk rate for that. That puts us at 12 stats. We’ve got three left.

Were it not part of the prompt, I would actually leave out defense stats entirely. Defensive metrics are still in the early stages of development, and I am not convinced that either defensive runs saved or outs above average tells us much that we don’t already know. If I have to pick one, which I do, I’ll take OAA.

We now have two stats left. I would be inclined to go a number of different directions, but, frankly, a baseball universe without innings pitched or plate appearances would be incredibly dumb. We need a way to track how many opportunities hitters and pitchers have had. For our last two stats, we will take innings pitched and plate appearances.

That leaves us with the following list:

1. AVG
2. OBP
3. SLG
4. OPS+
5. Barrel rate
6. Hard-hit rate
7. ERA
8. WHIP
9. ERA+
10. FIP
11. K%
12. BB%
13. OAA
14. IP
15. PA

The barbecue ranch salad is my go-to. I also tried the Thai salad recently and enjoyed it.

The Diamondbacks don’t play at Fenway Park this year, but attending or, better yet, covering a game there has always been a dream of mine.

Damon starts with the aux. Shawn comes next. Derek is restricted exclusively to singing along.

I have been unable to obtain a definitive answer on this, but it is probably safe to say that their roles would be minimal at most.

Brent Strom and Joe Mather are in the organization to help the D-backs get the most out of their players, not to find new players. The role of the scout and the role of the coach are quite different, and I would be surprised if there was much overlap.

Not that I am aware of, and I would be pretty surprised if that was a serious consideration. When Ketel Marte first came up in the majors as a shortstop, his biggest weakness on defense was not his range, but his arm. If he did not have a great shortstop arm back then, he probably does not have the arm for third base now.

According to Baseball Savant, Marte is averaging 79.8 mph on his top five percent of throws at second base this year. That is down from 83.8 mph last year and a tick below league average at that position. Obviously, that could tick up if he were asked to move to a position that demands more from his arm, but it doesn’t seem like a great fit.

All that said, it would be a nice fit on paper. Marte’s bat obviously would play well at third base, and the farm system has more promising depth in the middle infield than the corners right now.

I would certainly explore it if I were them. He does not have much defensive value, but the D-backs would become too left-handed again the moment he walked out the door.

As long as the team has DH at-bats available, he fits nicely on the roster. He should be relatively affordable, too.

See my previous answer to Brandon Buckingham’s question. For good measure, I will add a couple of other names: Eduardo Rodriguez of the Detroit Tigers and Corbin Burnes of the Milwaukee Brewers.

Rodriguez been fantastic for the Tigers this year, although he does have a tricky opt-out clause that carries undeniable risk. He will likely opt out because he is having a great year, but if he gets hurt or drops off significantly down the stretch, the team that trades for him could be stuck with three more years at around $16 million per year.

Burnes is having a down year by his standards, but he is still a clear upgrade over what the D-backs have. He is under team control through 2024, so the D-backs would be able to run it back with him next year.

Obviously, Zach Davies had an outstanding outing, and that was the ideal outcome for all involved. If he had struggled, though, I am not convinced that it would have been his last chance.

The D-backs simply are not in a position to be removing starters from the organization, at least not until they have exhausted all possible avenues for getting them back on track. In Davies’ case, there wasn’t a noticeable drop-off in stuff, and his peripherals suggested he was unlucky. It simply would not have made sense to move on from him at that point.

With Merrill Kelly now on the injured list and Brandon Pfaadt far from a sure thing, such a move would already look disastrous had they made it.

Here is a crazy one for you: the Czech Republic!

Seriously, it was hard not to fall in love with the Czech Republic’s squad in the World Baseball Classic. Their team was comprised of sales managers, high school teachers and electricians.

I spent a semester in Budapest during my college years, and I am still disappointed to this day that I never made it out to the Czech Republic while I was in the area.

I’m not sure baseball is fully ingrained in that culture just yet, but seeing a major league game there would be a fun, full-circle moment for me.

Follow Jesse Friedman on Twitter

Top photo: Jamie Sabau/USA TODAY Sports