It was only four years ago when Madison Bumgarner raised his arms above his head and staked his name atop the baseball world. He had just finished the most dominant postseason in history, and his team had capped off a dynasty.
But four years can feel like a lifetime in baseball, and on Monday, MLB.com's Jon Morosi reported that new president of baseball operations Farhan Zaidi is willing to talk with rival clubs about a possible Bumgarner trade. It's jarring to imagine Bumgarner in any other uniform, but the Giants might need to trade their ace to avoid falling further behind the pack. What's more, there's a host of warning signs that suggest San Francisco should trade Bumgarner now instead of waiting for next July's non-waiver Trade Deadline.
The questions surrounding Bumgarner begin with his health. Though each of his injuries -- a sprained AC joint in his pitching shoulder from a dirt-bike accident and a broken finger from a line drive -- were random in nature, it's up to both Zaidi and rival front offices to determine how much they affected Bumgarner's declining fastball. The lefty's cutter -- his primary pitch these days -- lost nearly 1 1/2 miles per hour in 2018 compared to the previous year. Bumgarner's overall fastball arsenal, pairing his cutter with his sinker, was hit often and hit hard once he returned to action.

Bumgarner has never lit up the radar gun, but it's hard to excel in today's game with a fastball under 90 mph. Even if Bumgarner's injuries were of the freak variety, it's hard to ever get that fastball velocity back. His declining heater already evoked ripple effects across the board -- including his lowest strikeout rate (19.8 percent) and highest walk rate (7.8 percent) and FIP (3.99) as a full-time big leaguer -- in 2018. Bumgarner's expected weighted on-base average (xwOBA), a Statcast™ metric based on strikeouts, walks and quality of contact allowed, tells a similar story of an ace trending the wrong way.
Bumgarner's xwOBA from 2015-18
2015: .272 (13th best of 136 qualified starters, minimum 400 batters faced)
2016: .281 (Tied for 14th of 140)
2017: .308 (Tied for 33rd of 136)
2018: .320 (Tied for 84th of 134)

Even beyond the numbers, there's concern for either the Giants or whoever else employs Bumgarner moving forward. Though he's still only 29 years old, Bumgarner's 1,638 1/3 career innings outrank anyone else his age, and are more than many older pitchers including Mike Leake, J.A. Happ, Jordan Zimmermann and Jeff Samardzija have thrown (he's also compiled an additional 102 1/3 frames in the postseason). Bumgarner is also a fly-ball pitcher who's likely benefited from cavernous AT&T Park, and the deep outs he induced in San Francisco could clear the wall in smaller home parks.
Fangraphs' Steamer projections currently believe Bumgarner will accrue 2.1 fWAR in 2019, an equal value to much less heralded starters like Kevin Gausman, Mike Minor and Joe Musgrove. You can bet rival teams are aware of all these trends, and so it might already be tough for Zaidi to find the return Giants fans would crave for a franchise icon like Bumgarner. If both San Francisco and its ace get off to slow starts in 2019, the market might be even more bleak by next summer's Deadline.

Bumgarner's track record and competitive spirit means it wouldn't be shocking at all if he still found ways to compete. He and Dodgers ace Clayton Kershaw both have some things to prove in 2019, and perhaps each could benefit from throwing their curveballs more: Bumgarner's curve has been one of MLB's best since Statcast™ began tracking in 2015. All that remains to be seen, but in the meantime there could be a handful of contenders who believe that Bumgarner -- who's owed just $12 million for the final year of his contract -- can get them over the hump as a cheap rental next season. Here's where he could fit in '19:
Brewers
Morosi mentioned the Brewers as a team that's already reached out to the Giants about Bumgarner. The Crew blurred the lines between starters and relievers with great success last season, but if Bumgarner can take the ball every fifth day, maybe it wouldn't need to lean on that bullpen quite so often before October. Milwaukee's right-handed prospects Corbin Burnes or Brandon Woodruff would instantly become one of the best arms in San Francisco's depleted farm system.
Phillies
This is the other club mentioned by Morosi as an interested party, and Philly's aggressive approach to this offseason puts it in just about every mix. The Phillies' rotation -- topped by righties Aaron Nola, Jacob Arrieta, Nick Pivetta and Vince Velasquez -- certainly could use a lefty, and the Phils' top-10 farm system should yield someone who catches Zaidi's eye.
Braves
Signing Josh Donaldson showed Atlanta is all-in on building off its 2018 success, but its rotation could still use another arm to bolster an emerging corps of Mike Foltynewicz, Sean Newcomb, Kevin Gausman and Julio Teheran. The Braves boast an even better farm system than the Phillies, so perhaps a trade for Bumgarner could help them stay ahead in the National League East.
Angels
The Halos have to start building a contender around Michael Trout, now just two years away from free agency. If Bumgarner's injuries were flukes and he can become a 30-start, 200-inning starter again, that's a pitcher Los Angeles desperately needs.

Astros
If any front office would be cognizant (and perhaps wary) of Bumgarner's downward trends, it would be Houston's. On the other hand, the Astros have proven they can boost a starter's performance by presenting data and suggesting pitch-mix changes. Maybe they can help Bumgarner kickstart the second half of his career.
Yankees
Bumgarner's fly-ball tendencies, as mentioned, wouldn't bode well in a park like Yankee Stadium. But the pinstripes have been as forward as any team about acquiring another starter, and former Yankee Alex Rodriguez already floated the idea this past summer.
Nationals
A top three of Max Scherzer, Stephen Strasburg and Bumgarner certainly wouldn't lack name recognition, and the rotation appears to be a focus for general manager Mike Rizzo this offseason. As The Washington Post's Chelsea Janes recently noted, Rizzo hasn't traded for an established starter since he acquired Doug Fister five years ago. Perhaps the time is right to pull off another deal.
Athletics
The A's are coming off a storybook season, but the state of their rotation means they can't afford to stand pat. Bumgarner could stay in the Bay Area and continue to play in a pitcher-friendly park.