Just before reporting to Spring Training 2017, Ketel's mother told him she wanted 10 home runs in the upcoming season. Marte had never hit double digit home runs in a season before so this was quite the request. According to Baseball Reference, the most home runs in a season (majors minors) he had hit before 2017 was 5 HR during 2015, hitting a mere 2 in 2016.

After being traded to the Diamondbacks in the off-season, Marte had to adjust to a new team and organization. Luckily it didn't take long with the familiar face in Taijuan Walker accompanying him to desert. He started his 2017 campaign in the minors, hitting 6 home runs with the Reno Aces before being called up June 28th, after Nick Ahmed's hand was fractured by a fastball from Cardinals reliever Trevor Rosenthal.

Now in The Show, Marte continued to achieve the unthinkable: the elusive 10 HR season. Marte started off slow but hit his 3rd MLB HR, 9th HR total for the 2017 season, on July 26th against the Braves with a rare stand-up inside-the-park homer against the Braves' Aaron Blair.
Marte's 4th MLB HR and 10th in the season came with a two-run blast off Cardinals reliever Kevin Siegrist in the 8th inning on Saturday, July 29th. During a post-game interview Marte shared this story about his mother:

“When I was playing softball in the Dominican (during the off-season) with my friend, she saw me hit a long homer. One day, before I came to spring training, she said, ‘I want 10 homers this year.’ Now, I’ve got 10 homers. When I hit my last homer, I called her. She had watched the game. I said, ‘Now you’ve got 10 homers, how about that?’ She was crying. It’s a crazy moment for me right now.”

Following the game the next day on Sunday July 30th and just before boarding the plane to the next series, Ketel once again called his mother, speaking briefly. Elpidia Valdez, Ketel's mother, was involved in a car accident not long after that call. When Ketel's flight landed he got word of the accident but was told she would be alright, giving him some piece of mind as he joined his teammates out for dinner. Shortly after, he received word that his mother had passed away. Marte would fly out to the Dominican Republic to be with his family and was placed on the bereavement list.

Marte was stricken with grief, trying to make sense why such a thing would happen. He took to social media to vent his emotions, making this heartbreaking post on his Instagram page.
Translated roughly it reads:

"Why did you leave my sweet love I love you my love why did you leave me all alone and not enjoy life with me enjoy mami this beautiful year I'm having you told me that you wanted 10 home runs you have them so why do you leave without seeing me my love come back mami please don't leave me all alone cause I love you my love come back my negra come back because the pain is killing me mami 😭😭😭😭😭😭😭😭😭😭"
Negra in this context is a term of endearment; it translates directly to black girl/woman.

With the encouragement of his family, Ketel rejoined the Diamondbacks on Friday, August 4th. He sat out that first game due to his absence from baseball but manager Torey Lovullo assured Marte that he was included in the lineup for Saturday. Ketel accomplished the goal set for him by his beloved mother.

Marte continued to hit well but did not register another home run until September, a solo shot against the Rockies. During the postseason Marte faced Dodger ace Clayton Kershaw hitting a bullet down the left field line for a solo shot at the top of the 7th inning
But the real magic came during the Wildcard where Ketel Marte hit two triples from each side of the plate, becoming the first person in postseason history to accomplish this feat.
2017 was only a taste of what Marte was capable of and what his mother saw in him. Marte has shown he can strike from both sides of the plate, driving him closer to making history once again with a swing of the bat.

In 2018, Marte continued to grow as a player. And this year has truly been something special. June 24th's game against the Dodgers was Marte's 7th straight multi-hit game, tying a franchise record with Luis Gonzalez. In the month of June, there have only been 3 games where he didn't reach base. He is currently in the top 10 in the MLB for batting average with .312 as well as for OPS with .976. He also has a chance to break the single-season record for most games with home runs hit from both sides of the plate. He has 3 so far this season and the record is 4, set by Ken Caminiti in 1996. On top of all that, he added center field to his resume this year to replace AJ Pollock. He continues to play both 2nd base and center field, as well as the occasional short stop, and has been an impressive athlete in all positions.

So if you're looking for a new favorite player to watch, look no further than Ketel Marte. He has broken out.

Thank you /u/hiciao for contributing to this write-up.