On the heels of a surprisingly successful season, the A's announced on Monday that they reached agreements on long-term extensions with executive vice president of baseball operations Billy Beane, general manager David Forst and manager Bob Melvin.

Terms of the deals were not immediately disclosed. The San Francisco Chronicle reported that Melvin's deal will run through 2021 and is valued at $3.5 million per season, which would make him one of the top five best-paid managers. The Chronicle also reported that Forst's deal runs through 2023. Beane is expected to remain immersed in the club's operations given his ownership stake.

With a style of play reflective of the climate of baseball in 2018, the A's won 97 games and reached the postseason via the second American League Wild Card spot. They lost to the Yankees in the AL Wild Card Game.

Oakland thrived on power-hitting offense, elite defense, a versatile, lights-out bullpen and capable starting pitching. And it did so as a relative surprise to most outside of the organization, particularly in light of having the Majors' lowest Opening Day payroll, according to Cot's Baseball Contracts, and within a competitive AL West that housed two other clubs that finished with winning records.

"I'm proud of the tremendous success of our team under the leadership of Billy, David and Bob and am excited to have that continue for years to come," A's managing general partner John Fisher said.

The contract status for Oakland's trio had been a topic of some uncertainty dating back to last offseason, as none of the three had deals in place beyond 2019 and the club had undergone significant changes on the business side. Melvin, for instance, was requested by the Yankees to interview for the managerial opening that went to Aaron Boone but was denied by Oakland ownership, and the A's didn't extend Melvin at the time or give him a salary increase.

"As far as the roster is concerned, we were all going to be here for '19 no matter what," Forst said. "So we've been working on that and thinking about '19 for a while. But certainly beyond, we have a young core that we hope is here into a new ballpark. So yeah, it helps clarify things there. The other part of it is running the organization and the stability of player development and scouting, Bob's coaching staff -- all these things that you think about wanting to have in place. Having the three of us signed goes a long way towards making sure that those things happen too."

"From the moment I got here, it's always been a special place for me for a lot of the reasons I've always talked about in the past," Melvin said at a press conference on Monday. "It just seems like every year, it gets more and more comfortable for me being at home. The people that you work for, the continuity in the organization, certainly the commitment now to going forward to a new venue and some of the players that we have here, so in the last couple of years in particular to really turn the corner as far as what you saw on the field last year, we feel like we can get better. 

The 57-year-old manager has been with Oakland since 2011 and overseen four postseason appearances. He is the favorite to win the AL Manager of the Year Award, which would be his second with the A's. He also won the 2007 National League Manager of the Year Award with the D-backs, with whom he spent parts of five seasons. He also managed the Mariners from 2003-04. Beane said earlier this month that he'd like to keep Melvin in Oakland for the rest of Melvin's career.

"This has kind of always been the place for me," Melvin said. "I've been a couple other places before that but the minute I got here and going forward, I knew really this is the one place that I wanted to be and wanted to stay. It doesn't happen very often in the baseball world now that you're in a place as long as I have been in my position, so I'm just proud to be an Oakland A."

Under Beane, who is recognized as a pioneer of sorts for scouting and developing talent in today's environment, the A's have compiled a 1,793-1,607 (.527) record in 21 seasons, which is the AL's fourth-best record and seventh-best in all of baseball during that time. They've won six AL West titles and claimed three AL Wild Card spots. Beane joined the club's front office in 1990 as a Major League advance scout under former GM Sandy Alderson, then was promoted to Alderson's post after the 1997 season. He was promoted to his current position after the 2015 season.

Forst has worked alongside Beane for nearly that entire time, having joined the club in 2000, working his way up from assistant GM and then to his current post, which he's held since October 2015.

Beane outlined on Monday that Oakland's blueprint for success will largely be grown organically. Many of its talented nucleus were drafted and developed within the Athletics' farm system, such as first baseman Matt Olson and third baseman Matt Chapman, who were both selected in the first round of the 2014 Draft and who emerged as elitists on both sides of the ball in 2018. Lou Trivino, an 11th-round pick in 2013, emerged as one of the best bullpen weapons in the Majors. 

• Chapman, Olson named Fielding Bible Award winners

Oakland has also been highly effective in the free-agent and trade markets. Since acquiring him from the Brewers ahead of the 2016 season, designated hitter Khris Davis has hit an MLB-high 133 homers. Blake Treinen, who they acquired from the Nationals, posted the eighth-lowest ERA (0.78) by a relief pitcher on record (since 1913) last year. Shortstop Marcus Semien, who was acquired from the White Sox, and relievers Fernando Rodney and Jeurys Familia, who were acquired from the Twins and Mets, respectively, were also paramount to Oakland's return to the postseason, as was outfielder Stephen Piscotty, who was traded from the Cardinals.

Beane said on Monday that the A's will continue to map out their long-term personnel strategy in a similar manner: by effectively striking in the Draft and making acquisitions externally that make economical sense. In the copycat world of baseball, Beane doesn't envision going blow for blow in the free agent and trade markets with the World Series champion Red Sox, who had the Majors' highest Opening Day payroll, three and a half times greater than Oakland's. 

"Listen, copycat, that's a great team," Beane said. "It's the best team I've seen since 1998 with the Yankees. You may want to copy them, but the ability to do so isn't so easy ... If we're going to copy them, we're going to try and do our best, but it's a pretty lofty goal for anybody."

Beane did add, however, that he envisions Oakland operating with a higher budget in 2019. 

"I would expect that to be the case," Beane said. "We're going to take a little more strategic view and look at it over a little more of a longer period of time instead of just one year at a time, which I think is a good way to do it. We're having those conversations now. To give you a simple answer now, yes, the payroll, we anticipate the payroll going up."

Beane also said that a primary offseason goal will be to fortify the starting rotation, which was Oakland's most glaring thorn. Even in an era where premiums are ever-increasing for the role of relievers, Oakland bullpened the AL Wild Card Game by starting reliever Liam Hendriks as an opener. That start would've likely gone to left-hander Sean Manaea had he not suffered a season-ending left-shoulder injury. 

"Everyone is chasing that great rotation," Beane said. "Very few teams have it. It costs a lot of money if you're going to go out there and buy it. Ideally, it's created organically through the Draft. If you look at probably the ideal rotation is a club like Houston, where they essentially have two or three guys that could pitch as a No. 1 for most of the league. We have some really good guys coming."

Specifically, Oakland's top two prospects -- left-handers Jesus Luzardo and A.J. Puk -- are in the pipeline and will be key cogs to their long-term rotation. Puk underwent Tommy John surgery in April and is expected to be back at some point in 2019. Luzardo's rapid ascent through the Minors was stalled some with struggles at Triple-A Nashville, where he gave up 13 earned runs in 16 innings after compiling a 2.12 ERA over 19 outings with Class A Avancedq Stockton and Double-A Midland. 

The A's will enter Spring Training with most of its 2018 roster intact. Their free agents include left-hander Brett Anderson, right-handers Familia, Trevor Cahill, Edwin Jackson, Shawn Kelley, outfielder Matt Joyce, infielder Jed Lowrie and catcher Jonathan Lucroy.