WASHINGTON --The Washington Nationals have won four National League East division titles since 2012 under three different managers.But the Nationals are still looking for a postseason series win and some stability in the dugout, as the club announced Friday that manager Dusty Baker will not return in 2018 after his two-year contract expired.Washington general manager Mike Rizzo said he called Baker on Friday morning and the former All-Star outfielder handled the news with professionalism. The previous manager, Matt Williams, also lasted just two seasons."It was one of the most difficult decisions the ownership group and I have had to make," Rizzo said on a conference call with reporters. "Dusty has been a great representative of the Washington Nationals for his tenure here -- a Hall of Fame-type manager."The Nationals won the National League East in both seasons under Baker in 2016 and 2017 and lost at home in Game 5 each year in the NLDS. Washington won 95 games in the first year under Baker and was 97-65 this year and won the division by 20 games."I'm surprised and disappointed," Baker told USA Today Sports. "They told me they would get back to me and I told them I was leaving town yesterday and they waited 10 days to tell me. I really thought this was my best year. We won at least 95 games each year and won the division back-to back-years but they said they wanted to go a different direction. It's hard to understand."The Nationals lost in the first round to the Los Angeles Dodgers in 2016 and to the Chicago Cubs this year. Baker came under fire for some of decisions this year in the playoffs.One of the most notable was not pinch-hitting for slumping catcher Matt Wieters with the bases loaded in Game 5 against the Cubs. Soon after that Baker took out Wieters on a double switch and brought in reserve Jose Lobaton. The Nationals led 4-1 but lost 9-8 in the deciding game to the Cubs. Baker also used lefty reliever Sammy Solis against the Cubs when several veterans in the bullpen were available."We have come such a long way in the Nationals organization," Rizzo said. "Now our expectations have grown to the fact that winning a lot of regular-season games and winning divisions is not enough."Rizzo said contract negotiations with Baker did not figure in the decision. Rizzo had said before the playoffs began he hoped to bring Baker back."This was a pure baseball decision. Our goal is win a world championship," Rizzo said. "After Game 5 ... we felt this was the right decision to make."Baker previously managed the San Francisco Giants, Cubs and Cincinnati Reds. He has lost the last 10 games in the playoffs in which his team had the chance to advance.The California native won a World Series title as an outfielder for the Los Angeles Dodgers in 1981 but has never won a Fall Classic as a manager. Baker has won 90 games 10 times as a manager and he won 103 games in his first year with the Giants in 1993.Davey Johnson led the Nationals to the 2012 division title and Williams was the manager of the year in 2014 when Washington won the division. Williams was fired after the 2015 season and the Nationals reportedly wanted to hire Bud Black, but he felt the Washington offer was not up to par, according to reports, and the Nationals went with Baker. Black led the Colorado Rockies to the playoffs this year.The Nationals enter the 2018 season with right fielder Bryce Harper and second baseman Daniel Murphy entering the final year of their contracts. Washington figures to contend for years to come in a weak division (for now) with Max Scherzer and Stephen Strasburg at the front of the pitching rotation.Washington also announced that the contracts of the coaches all expired. The hitting coach was Rick Schu and the pitching coach was Mike Maddux both years under Baker. The Washington offense slumped mightily in the playoffs against the Cubs, with Washington losing games in which Scherzer and Strasburg both had no-hitters early on."We are going to open up the list of (possible) managers and do our due diligence," said Rizzo, repeating one of his favorite phrases. "We will find the right person to get us to the next level."Rizzo said he did not take any input from players in deciding not to retain Baker."Our goal has never wavered -- a parade down Pennsylvania Avenue," Rizzo said.If that ever does happen Baker will not be in front of the victory parade. Baker, 68, was the oldest manager in the majors after Terry Collins of the New York Mets resigned after this season.