The San Francisco Giants played according to the script of their front office on Monday night. Chris Stratton, who is quickly establishing himself as a reliable force in the rotation, threw well against the Nationals, and there was some power, this time from Mac Williamson, who clubbed a baseball to a spot right-handed hitters almost never reach in AT&T Park.

But if there are not a lot more good days for the Giants before the July 31 trade deadline -- if they drift out of contention in the National League West -- then the team should do everything it can to steer around the abyss that swallowed the Phillies in recent seasons. If the Giants struggle over the next couple of months, they should take October legend Madison Bumgarner into the trade market.

A rival evaluator chatted about the Giants earlier this month, about the accumulation of players who could be on the downslope of their respective careers. “They have to get restarted and start turning the page, and they don’t have a lot of ways to do that,” he said.

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Nope. If the Giants turned into sellers, they wouldn’t get much in return for Andrew McCutchen, not when McCutchen is just a few months from becoming a free agent. First baseman Brandon Belt just turned 30 the other day and is owed about $65 million through the 2021 season, and given how the market for first basemen has been saturated, he has no trade value. The Giants owe 32-year-old third baseman Evan Longoria $60 million; even if San Francisco thought about flipping him, he would almost certainly have no trade value.

Shortstop Brandon Crawford could bring some return in a trade, but he’s owed about $55 million through 2021 and he’s kind of a specialty item with a limited market, because of what other contenders already have at the position -- the Astros have Carlos Correa; the Angels field Andrelton Simmons; the Yankees have Didi Gregorius; the Red Sox have Xander Bogaerts; the Cardinals just signed Paul DeJong to a long-term deal; the Mets have Amed Rosario; the Nationals have Trea Turner; the Dodgers have Corey Seager (not that the Dodgers and Giants would ever seriously consider a trade).

The assumption among other teams is that the Giants will never trade All-Star catcher Buster Posey, because he’s a legacy player and his long-term deal could reach through the end of his career. Johnny Cueto and Jeff Samardzija wouldn’t garner much trade return because of what they are owed.

But Madison Bumgarner? The Paul Bunyan of the postseason? The guy who threw more than twice as many innings as any other pitcher in the October when the Giants last won the World Series?

The left-hander would become the most coveted trade target in baseball -- maybe one of the most sought-after summer market pieces in baseball history -- if the Giants ever auctioned him off, and he would probably glean at least two high-end prospects for an organization thin on minor-league talent. “Maybe two top-tier guys and two second-tier guys,” said an evaluator. “I mean, if any team traded for Bumgarner, it would be [a move] to win the World Series.”

Yes. Because winning in the postseason is what Bumgarner does. In 16 postseason appearances, he has a 2.11 ERA, with the Giants winning all but three of the games in which he has appeared.

Last summer, the industry interest in Justin Verlander was high, but the Tigers’ ability to market him was complicated because of all of that was attached -- the right-hander’s no-trade clause; the $56 million owed to him for 2019-2020; his age, 35.

Bumgarner turns 29 the day after the trade deadline, and before he suffered the freak pinky injury on a line drive at the end of spring training, the Giants’ staffers felt he was throwing the ball as well or better than he ever has, with his velocity hitting 94 mph. He doesn’t possess any no-trade rights, under the terms of the deal he signed when he was very young. Bumgarner is making $12 million this year, and the Giants hold a $12 million club option for 2019, making him an incredible value.

A reasonable argument could be made that the Giants should do all they can to sign Bumgarner to an extension later this summer, and then build an immediate future around him and Stratton, while rebuilding the farm system. Those two starters could serve as the vehicle that helps the Giants transition from the core of those 2010-2014 championship years.

But if San Francisco takes that path, the Giants could fall into the same trap the Phillies did, as the championship generation of Ryan Howard, Chase Utley and Jimmy Rollins faded with age. By waiting too long to turn over the roster, the Phillies doomed themselves to a competitive drought which has now lasted almost as long as the glory years. The Phillies have not had a winning season since 2011, and in the past three years, they’ve totaled 63, 71 and 67 wins. Philadelphia is back on track this year.

If the Giants trade Bumgarner this summer or next winter, they also will avoid the quandary and risk of paying a pitcher for the downslope of his career. Bumgarner might reasonably demand a seven-year, $245 million deal, given his track record and the deals for Clayton Kershaw, Zack Greinke and others. Occasionally, those megadeals for an age 30ish elite starter can work out (see the Nationals and Max Scherzer). But mostly, they don’t work out, and if the Giants invest big dollars in a Bumgarner extension, they will have to assume that risk without taking advantage of his trade value. The Giants, one of the richest organizations in the game, could also aim to do what the Yankees did with Chapman: trade him for prospects, and then target him when he becomes a free agent.

The Giants of 2018 may turn out to be better than what they’ve shown early this season, and that would change the Bumgarner context. But if they don’t play better, then the Giants would be well-served to think about their clubs of 2021 and 2022; those are teams that appear to need a whole lot of help, and the Giants can get that if they’re willing to listen to offers to a pitcher who would be coveted by any contender.