In July, Denyi Reyes has made five starts for the Portland Sea Dogs, going 4-0 with a 0.94 ERA, with 21 strikeouts and four walks in 32 innings. Derek Davis/Staff Photographer

After four or five seasons, minor league baseball players can be chosen by other organizations in what is known as the Rule 5 draft – if those players are not placed on a major league 40-man roster.

Last fall, when the Boston Red Sox decided which prospects to protect on the 40-man roster, they made four predictable choices – infielder Michael Chavis, and pitchers Darwinzon Hernandez, Josh Taylor and Travis Lakins. No doubt those players could have been chosen in the Rule 5 draft; and all four have performed with Boston this season.

But the Red Sox surprisingly protected a fifth player last year, a right-handed pitcher who appeared in only six games in advanced Class A Salem.

Denyi Reyes, 22, does not blow away the radar gun – the fastball tops at 89 mph – and he is not high on anyone’s prospect list (mlb.com ranks him 27th among Red Sox prospects; soxprospects.com ranks him 38th). Yet the Red Sox feared another team might snatch Reyes.

“He has really good command of his four-pitch arsenal,” said Ben Crockett, the Red Sox director of player development.

In other words, Reyes may not be a flamethrower but he can pitch, with a fastball, slider, curve and change-up.

“He throws strikes with all four pitches, with deception,” said Portland Sea Dogs pitching coach Paul Abbott. “His fastball plays a lot more than what the (radar) gun reads.”

Reyes, who had a combined 1.97 ERA last year with low Class A Greenville and Salem, joined the Double-A Sea Dogs to start 2019.

Early on, Reyes could be dominant (back-to-back shutout outings in May) and he always stayed poised.

“One thing about Denyi, he doesn’t get too high or too low,” Abbott said. “You don’t know what the score is when you look at him pitch. He keeps executing pitches and stays in the game. He gives you a chance to win. That’s what you want in a starter.

“He’s been extremely impressive.”

July has been especially impressive, with Reyes making five starts, going 4-0 with a 0.94 ERA, with 21 strikeouts and four walks in 32 innings. On the season he’s 6-9 with a 3.77 ERA in 20 starts, allowing 105 hits in 117 innings with 91 strikeouts and 32 walks.

Crockett said Reyes is in a good place, “toward the end of a full year in Double-A.” But being on the 40-man roster means the clock is ticking on Reyes. He will be out of minor league options by 2022.

A promotion soon to Triple-A seems in order. The Red Sox need to find out if Reyes’ mix will play at the next level.

IF BOSTON DEALS prospects before Wednesday’s 4 p.m. trade deadline, Reyes conceivably could be part of a package.

Who else might Dave Dombrowki, the Red Sox president, deal to upgrade the 2019 club? The answer is almost anybody, depending on the deal.

There may be only a few untouchables in the Red Sox farm system – Sea Dogs pitcher Bryan Mata (Boston’s best chance at a homegrown starting pitcher), corner infielder Triston Casas (impressing in Greenville – .833 OPS – a year out of high school), and center fielder Gilberto Jimenez (tearing it up in Lowell, hitting .358 with an .835 OPS).

Sea Dogs corner infielder Bobby Dalbec could be dealt if Boston is going after a big fish (say, Mets reliever Edwin Diaz). Boston has corner infielders in Chavis and Rafael Devers, to name a few. Dalbec offers power and plate discipline (20 home runs and 66 walks this year) but is batting .230.

Another trading chip from the Sea Dogs’ infield is shortstop C.J. Chatham, who is batting .299 but is blocked in the majors by Xander Bogaerts.

NOTES: The Red Sox signed utility player Chris Owings, 27, after the Royals released him June 4. In 33 games in Pawtucket, Owings is batting .341 with nine home runs. … Portland reliever Adam Lau blew a save Sunday but his ERA rose to only 3.06. Lau, 25, may remind people of the late Rod Beck who, like Lau, lived in a travel trailer during his minor league days. Unlike Beck, Lau does not park his trailer at the ballpark. He and his wife live in Wells. … Right-handed pitcher Chase Stugart (12th round, 2018, out of the University of Texas), has made 12 starts for Greenville (2.00 ERA/1.17 WHIP). … In radio announcing “prospect” news, Sea Dogs play-by-play man Mike Antonellis will call the Pawtucket Red Sox games this week. Meanwhile, Salem’s Melanie Newman is getting called up to handle the Sea Dogs play-by-play.