In June 2017 Seattle shortstop Jean Segura was one-plus years away from free agency when the 2018 All Star signed a five-year, $70 million extension with the Mariners with a $17 million team option for a sixth year.
Boston shortstop Xander Bogaerts, who is two-and-a-half years younger than Segura, is one-plus years away from free agency.
Segura has posted 15.0 fWAR in 844 career games, including 3.1 fWAR and 2.9 bWAR in 87 games this season. Segura had posted about 11 fWAR in 675 games when he signed the extension in June 2017.
Bogaerts has posted 15.9 fWAR in 699 games, including 2.9 fWAR and 2.0 bWAR in 76 games this season.
Bogaerts and Segura each had a monster 2016 season. Since the start of that season, Bogaerts has posted 11.1 fWAR in 381 games while Segura has posted 11.1 fWAR in 365 games:
https://www.fangraphs.com/leaders.aspx?pos=all&stats=bat&lg=all&qual=y&type=8&season=2018&month=0&season1=2016&ind=0&team=&rost=&age=&filter=&players=
I doubt Bogaerts and agent Scott Boras will agree to an extension, certainly not a five-year, $70 million extension.