Having failed to make this year's postseason, the Seattle Mariners are now 0-for-their-last-16 in reaching the playoffs -- a stretch dating back to that magical 116-win 2001 squad.

What's more disappointing: that the M's failed to build upon last year's momentum, when they were in it 'til the final weekend, or that they could finish 20-plus out in the American League West, a symbolic reminder that the Houston Astros were that much better? Maybe it's that the Mariners' aging core is another year older? Or, perhaps, the real answer is this: general manager Jerry Dipoto will enter the winter with an agenda that looks like the one he faced last winter. Chef among Dipoto's objectives: buttress the rotation.

Sure, Dipoto could stand to tinker with his lineup. He'll have to, since first basemen Yonder Alonso and Danny Valencia, and center fielder Jarrod Dyson are impending free agents. But the position players did their part, providing some of the best defense in baseball while ranking mid-range in most meaningful offensive categories. That's a win, given how thin the lineup looked entering the year. The bullpen wasn't awful, either. Dipoto would undoubtedly like to see a sharper Edwin Diaz, and will probably add a piece or two. Ho hum, business as usual.

The real intrigue, however, is what Dipoto will do to complement his starting five.

Remember, entering the season there were serious concerns about the M's rotation's reliability in health and performance. Those reservations proved correct: Ariel Miranda is the only Seattle pitcher to start more than 24 times ... and he leads the majors in home runs allowed. Yikes. Drew Smyly missed the entire season. Yovani Gallardo was awful and missed time. James Paxton was great and missed time. And so on -- it's not a great sign when Andrew Albers and Sam Gaviglio combine for nearly as many starts as Felix Hernandez and Hisashi Iwakuma.

usatsi-10211007.jpg
A sight Mariners fans hope to avoid seeing in 2018. Joe Nicholson / USA TODAY Sports

Dipoto spent the summer doing what he could to weather the season while building for the future. Hence acquiring Mike Leake (and Mike Leake's contract), Marco Gonzales, and Erasmo Ramirez.

The problem is there's still room for shoring up. Leake has been excellent with the Mariners, but is historically more of a mid-rotation guy than a frontline starter; Gonzales could turn into the new Jason Vargas -- he's yet to, however, and he'll enter next spring as a 26-year-old; then there's Ramirez, who in the past few seasons has been shipped from Seattle to Tampa Bay, rotation to bullpen, Tampa Bay to Seattle, bullpen to rotation. Collectively, there's one sure thing there to plug in alongside Paxton and Hernandez -- the latter of whom is no longer an impact-level talent.

How will Dipoto ensure that what happened this year doesn't happen next year? It's unclear. The Mariners don't have much of a farm system to deal from, and have more than $113 million in outstanding commitments for 2018. (That figure doesn't include arbitration raises, but it does include bidding adieu to Gallardo and Iwakuma.) The free-agent market offers more starting pitching talent than was available last winter, so perhaps Dipoto has designs on casting his line and catching another mid-rotation arm. (It's entirely too early to speculate on who, though it would be amusing if Dipoto added another former St. Louis Cardinals starter, like Lance Lynn or Jaime Garcia, to his collection.)

Whatever the Mariners do, Dipoto will need it to go better than last year. If he enters next winter with this same problem, then, who knows -- maybe they'll no longer be his problem to solve.