PHILADELPHIA -- The Phillies' most important offseason in more than a decade officially started on Monday.
Everybody expects them to be one of the most aggressive teams in baseball and likely serious challengers for free-agent superstars Bryce Harper and Manny Machado. Yes, the Phillies have money to spend, but they also know they cannot throw money at every problem. They will need to make smart trades, too. They will need the players they keep to develop further in 2019. They will need the culmination of those decisions to send them to the postseason next fall.
Here are five of the Phillies' Hot Stove storylines to watch:
Bryce or Manny?
Harper might be the frontrunner, if for no other reason than he did not have a tumultuous postseason like Machado. (Harper's Nationals missed the postseason, but that is beside the point.) Machado's postseason antics have soured some Phillies fans, but sources indicate the club will pursue him, even though he has given them a little more to consider. The Phillies are aware of the potential blowback the first time (or every time) Machado does not hustle down the first-base line. But the Phillies are smart enough to know that Machado is one of the best players in baseball. They cannot dismiss him just because of his "Johnny Hustle" comments and behavior toward the Brewers and their fans in the National League Championship Series. Machado can fast track the Phillies back to the playoffs.
• Complete list of free agents this offseason
The Harper and Machado sweepstakes will dictate everything else the Phillies do this offseason, which makes this winter so difficult to project. If the Phillies land Harper, the dominoes fall one way. If they sign Machado, the dominoes fall another. And if they sign neither, the dominoes fall in an entirely different direction. That means it is difficult to project who might or might not be traded, other than Aaron Nola and Rhys Hoskins -- they aren't going anywhere.

The rest of them
The Phillies might not pursue second-tier free agents because they essentially already have those players. In other words, they might not want to drop tens of millions on an outfielder when they have already have Nick Williams, Odubel Herrera, Roman Quinn and Aaron Altherr. The Phillies are thinking big this winter.
Can Santana and Hoskins co-exist?
Hoskins would like to play first base. Expect the Phillies to listen to offers for first baseman Carlos Santana, but it will take the right deal. If the Phillies do not trade Santana, can they make it work? Possibly. When the Phillies have a fly-ball pitcher on the mound, they could play Santana at third base and Hoskins at first base. When ground-ball pitchers like Nola and Jacob Arrieta start, they could play Hoskins in left field and Santana at first.

The starting five
Phillies general manager Matt Klentak has said he prefers to avoid the starting-pitching market because of the high cost. If that holds true, it is difficult to imagine the Phillies pursuing free-agent left-hander Patrick Corbin with the same gusto as Machado and Harper.
But if the Phillies make a move to upgrade the rotation, they are likely to acquire a left-hander, which would give them a little more balance. In that scenario, perhaps the Phillies move Vince Velasquez to the bullpen or make a trade to clear room for the lefty.
Hoskins, Nola extensions?
The Phillies signed infielder Scott Kingery to a six-year, $24 million contract in March, before he played his first big league game. If Philadelphia wants to lock up another next young talent, Nola and Hoskins are the most logical options. Nola is a bona fide ace, but he is not eligible to become a free agent until after the 2021 season. Hoskins is the face of the franchise, but he is not eligible to become a free agent until after the '23 season. Nola might more amenable to an extension, if for no other reason than there are more health risks for pitchers than position players. Hoskins' long-term viability became a little more complicated once he chose Scott Boras as his agent. But at the moment, the Phillies have bigger fish to fry than extensions for Nola and Hoskins. It seems like something that might happen further down the road.