Jon Lester became the most important signing in Cubs history when he agreed to a six-year, $155 million contract to be the ace of the Cubs.

He spurned his old team — the Red Sox — along with a handful of other teams ready to pony up the nine-figure deal necessary to acquire the frontline starter. By choosing the Cubs, Lester accelerated Theo Epstein & Jed Hoyer's famous "Plan," legitimizing Chicago as a free agent destination and as an up-and-coming perennial playoff team.

"This signing really marks a transition of sorts for the Cubs, the start of a period where we are clearly very serious about bringing a World Series to the Cubs and the people of Chicago," Epstein said back on Dec. 15, 2014.

Inking Lester to a megadeal was a calculated risk, but all $100 million contracts are. Here's a closer look at the Cubs 100 million dollar men:

Nov. 30, 2006 - The Cubs introduce Alfonso Soriano

Back in 2007, the Cubs needed to make a splash and did so by signing the top free agent hitter on the market.

The Cubs inked Alfonso Soriano to an eight-year, $136 million dollar contract — then, the largest in franchise history. The Cubs had their leadoff hitter — fresh off becoming the fourth member of the 40-40 club — to go along with a new manager in Lou Piniella. Soriano made two All-Star teams for the Cubs in 2007 and 2008 while playing a key role on both division-title winning teams.

However, his time with the Cubs will often be remembered by his offensive decline, his subpar play in the outfield, and his eventual trade to the Yankees. While his overall body of work was statistically respectable, his output did not match the $136 million the Cubs invested in him.

 

Dec. 15, 2014 - The Cubs introduce Jon Lester

Like the signing of Soriano, the reeling in of Lester to Wrigley Field was paired with the hiring of another new big name manager, Joe Maddon.

Three years into his megadeal, Lester is 43-25 with a 3.33 ERA in 96 starts. The 2016 All-Star and Cy Young runner-up has done some of his best work in the postseason, where he's 3-1 with a 1.98 ERA in his last nine postseason appearances — three of which came in the 2016 World Series.

Lester's tireless work ethic off the field and his veteran influence in a young Cubs clubhouse has made this signing a smashing success. 
    
Dec. 15, 2015 - The Cubs introduce Jason Heyward

One year to the day after introducing Lester, Jason Heyward met with the Chicago media after signing an eight-year, $184 million contract — the richest in franchise history.

Heyward was coming off one of his best offensive seasons (.289, 13 HR, 60 RBI with the Cardinals) and his third Gold Glove in four seasons but the prized free agent struggled from the start in Chicago. Taking Heyward away from the Cardinals and signing baseball's top free agent prize ended up creating an outfield log jam in Chicago.

Heyward's speech during the rain delay in Game 7 against the Indians will most likely end up being the highlight of his Cubs career. The post-World Series championship offseason storyline of Heyward rectifying his broken swing was entertaining to follow on social media, but his 2017 slash line of .259/.326/.389 is clearly not worth the $184 million he signed for.

The future is now

"I believe in the plan that they have in place for the future of the Cubs."

That's what Lester said back on Dec. 15, 2014.

That statement still holds true today. Lester remains the anchor of the Cubs staff surrounded by Kyle Hendricks and Jose Quintana with reinforcements on the way. Regardless of any additions or subtractions, the Cubs will again be one of baseball's World Series favorites entering 2018 and the reliable lefty will be at the center of it all.

Halfway home, the $155 million deal has been "smart money" spent on Lester, the most important signing in Cubs franchise history.