That Tanner Roark has established himself as one of the best starting pitchers in baseball is remarkable enough, given the right-hander’s path to this point: a 25th-round pick in the 2008 draft who didn’t make his major league debut until he was nearly 27.

That the Nationals acquired this elite pitcher and rotation anchor from the Rangers six years ago in exchange for the final 15 games of Cristian Guzman’s career ... well, that’s almost beyond comprehension.

The Guzman-for-Roark trade deadline deal in 2010 - it also included fellow minor league pitcher Ryan Tatusko coming from Texas to Washington - is among Mike Rizzo’s finest in his eight seasons as Nationals general manager. And it’s not like there aren’t several other fine trades on Rizzo’s resume.

Indeed, Roark’s performance during yesterday’s 1-0 win over Madison Bumgarner and the Giants, not to mention his sustained excellence this season (now 12-6 with a 2.88 ERA), left us wondering where exactly his acquisition ranks among Rizzo’s best moves over the years.

Some quick research on every trade Rizzo has made since replacing Jim Bowden in 2009 reveals no shortage of potential candidates. In fact, it wasn’t easy paring down the full list to the mere top 10 trades of his tenure.

With the glow of Roark’s latest gem still on everyone’s minds, and with the Nationals off today, this seems like a good time for a review of the best trades of the Mike Rizzo era in Washington. We’ll do this in a countdown format, the rankings purely subjective by this humble reporter’s opinion. Please feel free to offer up your own rankings, or mention any other trades that didn’t make this particular list (or even to point out Rizzo’s worst trades, though there aren’t nearly as many in contention for that title) ...

10. Aug. 3, 2012: David Freitas to OAK for Kurt Suzuki and cash

With Wilson Ramos out for the season with a torn ACL and Jesus Flores struggling to replace him, the Nats desperately needed a quality starting catcher. Rizzo found one in Suzuki, who became a key part of the 2012 National League East champs and then the 2013 club as well. Freitas, a fellow catcher and 15th-round pick in the 2010 draft, has played seven seasons for four different organizations and has yet to reach the big leagues.

9. Feb. 13, 2014: Nathan Karns to TB for Jose Lobaton, Felipe Rivero and Drew Vettleson

Speaking of catching needs, the Nationals again needed catching help in the spring of 2014. They got it in the form of Lobaton, a solid backup with good defensive skills. Karns was highly thought of by some in the Nats front office, but his 4.41 ERA in 51 big league games with the Nationals, Rays and Mariners leaves much to be desired. Rizzo also got Rivero (a hard-throwing lefty who became a big part of the bullpen in the last year and then became the key piece in acquiring Mark Melancon) and Vettleson (an outfielder currently hitting .226 at Single-A Potomac).

8. July 30, 2016: Felipe Rivero and Taylor Hearn to PIT for Mark Melancon

Speaking of Rivero, Rizzo was able to turn the lefty into a two-month rental of Melancon, one of the best closers in the game. We won’t know for sure how this deal works out for some time, but the trade was met with a positive reaction from most corners of the baseball world, where Rizzo was lauded for acquiring his much-needed closer at a price that was far less significant than what it cost to get Aroldis Chapman or Andrew Miller.

7. Nov. 29, 2012: Alex Meyer to MIN for Denard Span

The Nats had a longstanding need for a good center fielder and leadoff hitter, and Span more than adequately filled that need for two of his three seasons in D.C. Injuries derailed his final season with the team, but there’s no debating his impact on the 2013 and 2014 lineups. Meyer, a first-round pick in the 2011 draft, was seen as perhaps the best prospect Rizzo had ever traded to that point. But the 6-foot-9 right-hander has yet to pan out and has dealt with injuries to boot.

6. June 28, 2009: Ryan Langerhans to SEA for Michael Morse

Little was made of this trade at the time. (It merited one paragraph at the end of beat writers’ daily notebook article.) But, boy, did it turn out to be a steal for the Nationals. Morse became a force in the middle of the Nationals lineup (not to mention a fan favorite) in 2011 and 2012. Langerhans? He hit .202 with a .673 OPS in 123 big league games for three different teams after this trade.

5. Dec. 22, 2011: A.J. Cole, Tommy Milone, Derek Norris and Brad Peacock to OAK for Gio Gonzalez and Robert Gilliam

Gonzalez may be erratic and drive you nuts sometimes watching him pitch, but let’s not forget he has been a mainstay in the Nationals rotation for nearly five seasons now, and a pretty good one at that. He’s 60-43 with a 3.49 ERA in 144 starts since the trade. The price to acquire Gio (three pitching prospects and a catching prospect) appeared to be awfully steep at the time, but none has realized his full potential in the five years since. Norris has been the best of the group, though a .237-hitting, defensively challenged catcher with occasional power has hardly outperformed the left-hander that came to Washington in the deal.

4. Dec. 2, 2013: Steve Lombardozzi, Ian Krol and Robbie Ray to DET for Doug Fister

There were plenty of Lombardozzi fans upset with Rizzo’s decision to deal the local kid away at the time, but how has that all worked out? Fister was a godsend for the Nationals rotation in 2014, and though he wasn’t the same in 2015, he still wound up making a significant impact on this organization. Krol has bounced around over the last three seasons, while Ray has flashed potential for the Diamondbacks (who acquired him after the 2014 season) but has yet to put it all together.

3. Dec. 19, 2014: Steven Souza Jr. and Travis Ott to TB for Joe Ross and Trea Turner from SD

This may well go down as Rizzo’s finest trade when it’s all said and done, but it’s just a little too early to award it that designation yet. We still don’t know for sure what Turner and Ross will be for the Nationals in the long run. The early returns, though, have been fantastic. Souza has taken advantage of his opportunity to play with the Rays (27 homers in 194 games) but he didn’t seem to have much future in D.C.

2. July 29, 2010: Matt Capps and cash to MIN for Wilson Ramos and Joe Testa

When he needed a rental closer at the deadline this summer, Rizzo gave up a promising-but-erratic reliever and a Single-A pitching prospect. When he had the opportunity to trade a rental closer to a desperate contender six years ago, he got back a starting catcher who has blossomed into an All-Star (and a left-hander who never panned out). Six years of Ramos for two months of Capps ... who do you think got the better of that deal?

1. July 30, 2010: Cristian Guzman to TEX for Tanner Roark and Ryan Tatusko

These are some of the most fun trades to reflect on because there wasn’t much reason to evaluate it at the time. The 93-loss Nationals were looking to shed Guzman and the remaining money on his contract at the deadline in 2010, and the Rangers were willing to acquire him in exchange for two minor league pitchers who didn’t have particularly impressive resumes. Tatusko was considered the better prospect of the two, but his career fizzled out quickly. As for that Roark kid ... well, you know the story by now. He’s 38-24 with a 3.05 ERA in 108 career games with the Nationals, who control his rights for three more seasons after this one. Not bad. Not bad at all.