Rosenthal: What’s gone wrong with the Mariners? Plus Yankees’ bullpen, Evan

Wait, wasn’t this supposed to be the Mariners’ year? Actually no, according to Baseball Prospectus’ projection of 83 wins and Fangraphs’ projection of 79. But actually yes, according to what general manager Jerry Dipoto told a Seattle radio station after trading left-hander James Paxton to the Yankees for three prospects in Nov. 2018.

Based on Dipoto’s comment — “We are going to re-situate our roster and look toward 2020, 2021” — the Mariners already are a year late. And uh, the calendar carries particular meaning for a team that has not made the playoffs since 2001, the longest drought in North American professional sports. In year four of the Mariners’ rebuilding, re-imagining, whatever you want to call it, they are in last place in the AL West, percentage points behind the deliberately putrid A’s.

True, the Mariners went 90-72 last season, contending until the final weekend. But they did it with a minus-51 run differential that, according to Bill James’ Pythagorean expectation, should have left them with a record closer to 76-86. It was a magical season, fueled by a resourceful offense and over-achieving bullpen. But few in the game thought the run was sustainable unless the Mariners made improvements. And they did. Or so they thought.

Dipoto traded for second baseman Adam Frazier. He signed free-agent left-hander Robbie Ray for $115 million. And when he was unable to land Kris Bryant or Trevor Story on the open market, he swung a trade with the Reds for left fielder Jesse Winker and third baseman Eugenio Suárez that seemed to address the team’s offensive needs.

So, why the heck are the Mariners 18-27 after starting the season 11-6? Because unlike last season, when everything in the final four months seemed to go right — remember the Mariners’ major-league best 33-19 record in one-run games? — everything for the last four weeks has seemed to go wrong.

On April 26, the Mariners were tied for third in the majors in runs per game and fifth in ERA. Since then, they’re 26th in runs per game and 28th in ERA, which pretty much explains their 7-21 record in this span. Those dead balls you’ve been reading about all season? Evidently the Mariners’ pitchers are using a different batch. They’ve allowed a major-league high 61 homers in 45 games.

And yet, for all the Mariners’ troubles, they do not look all that different than the Red Sox did when the Sox were 10-19. The Seattle offense is not at the level of Boston’s. The Seattle team overall probably is not as good as Boston’s. But it was inevitable the Red Sox, now on an 11-4 roll, would show improvement. The Mariners ranked only 22nd in Opening Day payroll and face an uphill fight to make the postseason even in an expanded format. Yet they, too, surely are better than they’ve shown.

“We feel like the talent is here,” Dipoto said. “We thought we were in a position to contend, and we still do. I know our players thought that way. There were various members of the media who felt that way. I don’t think anybody looks at our team and sees anything but frankly a team that has underperformed its ability. And we have. We just haven’t played well.”

Want to rationalize? It’s easy to rationalize.

• Regression was expected. FanGraphs determined the Mariners’ offensive performance in high-leverage situations last season to be the most clutch since it started tracking the metric in 1974. Dipoto said the bullpen had a magical year, in large part because the relievers (as well as the starters) got ahead in counts better than they have this season.

• Young teams experience growing pains. The Mariners’ position-player group is the second youngest in the majors. The pitching staff is the eighth youngest. Some of the young players (Julio Rodriguez, Logan Gilbert, George Kirby, Kyle Lewis) have produced fairly quickly. Others (Jarred Kelenic, Cal Raleigh, Evan White, Matt Brash) have not.

• Injuries depleted the lineup. Right fielder Mitch Haniger likely is out until July with a sprained right ankle. Catcher Tom Murphy is down with a dislocated left shoulder, infielder Abraham Toro with a left shoulder sprain. Still, as Dipoto put it, “We should be able to weather that storm. Other teams in the league are dealing with that, or more.”

Dipoto is a frenetic trader, and some of his past acquisitions (Haniger, J.P. Crawford, Ty France) were outright coups. At times he appears to be moving a lot of dirt without building anything. But the Mariners did not lose much off their 2021 roster, and their additions seemed reasonable enough. If the team did not appear as strong as the Angels and Astros, who ranked eighth and 10th, respectively, in Opening Day payroll, it certainly seemed poised to take another step forward.

So now what happens? Dipoto and manager Scott Servais received multi-year extensions last September. It’s difficult to justify firing hitting coaches from a team that, even after a…