Rosenthal: What I’m hearing — The Mariners are a team to watch at the trade

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As the deadline nears, the Mariners remain a team to watch. They have the one commodity virtually every other contender wants, controllable starting pitching. And as interest in their pitchers mounts, they are considering trading a starter for a package that would include a hitter of similar age and impact, according to sources briefed on their thinking.

The Mariners currently have four starting pitchers in their rotation between the ages of 23 and 26 — All-Star George Kirby, Logan Gilbert, Bryce Miller and Bryan Woo. They also have a potential starter-in-waiting, Emerson Hancock, 24, who was Texas League Pitcher of the Month for June.

If the Mariners traded a starter, they would want the players they obtained, combined with the promotion of Hancock, to enhance their playoff odds, which according to Fangraphs currently stand at 14.2 percent. The Rays, Orioles and Diamondbacks are among the contenders who could be a match. So could a non-contender such as the Cardinals, as mentioned earlier this week.

The Mariners’ bar for such a deal, though, is rather high.

The entire industry took notice Wednesday night when the Angels traded two of their best prospects, catcher Edgar Quero and left-hander Ky Bush, for a pair of rentals from the White Sox, right-hander Lucas Giolito and reliever Reynaldo López. Quero, 20, is the game’s No. 84 prospect, according to Baseball America’s updated rankings.

Controllable starters are far more valuable in the market than two months of Giolito. In fact, they are such coveted assets, a straight-up deal for a controllable hitter probably would not be of interest to Jerry Dipoto and Co., unless the hitter already was a star. Starting pitching is valuable. Starting pitching is fragile. The Mariners know, because they’re living it.

Robbie Ray made only one start this season before requiring flexor tendon repair and Tommy John surgery. Marco Gonzales is on the 60-day injured list recovering from a left forearm strain. Two advanced starting-pitching prospects, Easton McGee (elbow) and Taylor Dollard (labrum), also are out for the season, as is reliever Penn Murfee (elbow).

Baseball people will tell you that a pitching surplus can turn into a pitching shortage quickly. But perhaps the Mariners could work other avenues to maintain their rotation depth. One possibility would be expanding their trade of a starter to get another one back. Another would be moving a potential free-agent hitter in demand, right fielder Teoscar Hernández, for a rental starting pitcher.

A lot of bodies could end up flying around. The more a team tries to connect a series of deals, the greater the degree of difficulty. Still, the Mariners under Dipoto have not shied from dramatic in-season makeovers. They’ve got something everyone else wants. The question now is…