In his fifth season in the league and third with Oklahoma City, Grant broke through with an outstanding 2018-19 campaign. After serving as a reserve throughout most of his career, Grant started 77 of the 80 contests in which he played season, logging a career-high 32.7 minutes per game. Not surprisingly, the increase in minutes led to a slew of career per-game bests, including points (13.6), rebounds (5.2) and three-pointers (1.4). Grant also excelled on the defensive end, averaging 1.3 blocks per game, tied for 26th in the league. Grant's success wasn't all about volume. He also achieved career highs in three-point percentage (39.2) and free-throw percentage (71.0) while notching the second-best field-goal percentage of his career (49.7). The versatile veteran played his best basketball at the end of the regular season, averaging 18.8 points and 3.0 treys per game in five April contests. In the finale against Milwaukee on April 10, Grant racked up a season-high 28 points on 11-of-20 shooting, including 4-of-8 from deep. He followed the strong finish with a solid all-around effort in Oklahoma City's first-round playoff series against Portland. Despite the Thunder's five-game exit, Grant averaged a robust 35.2 minutes per game in the series, posting per-game averages of 11.6 points, 5.4 rebounds and 2.0 blocks. He was also effective from deep, making 9-of-20 shots from downtown.

In his first full season in Oklahoma City, Grant was a steady presence across 81 games of action. He started just once but averaged a healthy 20.3 minutes per game as a key member of the rotation for a playoff team. The Syracuse product averaged 8.4 points and 3.9 rebounds per game while shooting a robust 53.5 percent from the field, which marked a new career-high mark for him. Grant also set a new career-high mark by making 67.5 percent of his attempts from the free-throw line. He did most of his damage from inside the arc, as Grant shot a career-low 1.4 3-pointers per game. Defensively, Grant blocked at least one shot per game for the fourth straight year to begin his career. He scored a season-high 20 points in a win over Atlanta on March 13. It was an all-around strong performance for Grant that night, as he also grabbed five rebounds, blocked two shots and recorded two steals. Grant continued to produce in the playoffs, going for 13 points and six rebounds in Game 2 of an eventual first-round loss to Utah.

In his third NBA season, Grant spent time with both the 76ers and Thunder, appearing in 80 combined games. He began the season in Philadelphia, where he saw action in two contests, totaling 41 minutes. On Nov. 1, Grant was traded to the Thunder for Ersan Ilyasova and a first-round pick. He went on to make 78 appearances for Oklahoma City, posting averages of 5.4 points, 2.6 rebounds and 1.0 block in 19.1 minutes per game. The Syracuse product scored in double-figures nine times and recorded a season-high 15 points on two separate occasions. He hit 37.7 percent of his three-point attempts, including 43.1 percent of his looks from the corners. In a win over the Knicks on Feb. 15, Grant scored 13 points to go with five rebounds, two assists, two blocks and a steal in 24 minutes off the bench. He pulled down a season-high eight rebounds against the Clippers on Jan. 16 and matched that total on April 11 in Minnesota. In a loss to Portland on Dec. 13, Grant moved into the starting lineup for the first time in a Thunder uniform. In the postseason, Grant appeared in all five of the Thunder's first-round games against the Rockets. He scored in double-figures three times, including posting 11 points and five rebounds in Game 5.

Playing in his second NBA season, Grant appeared in 77 games and made 52 starts for the 76ers. The Syracuse product turned 26.8 minutes per game into averages of 9.7 points, 4.7 rebounds, 1.8 assists and 1.6 blocks. Grant hit 41.9 percent of his field goals, overall, while making 24.0 percent of his three-pointers and 65.8 percent of his free throws. In just the second game of the season, Grant went for 12 points, five rebounds, two assists and two blocks in 25 minutes off the bench. Two games later, on Nov. 4 in Milwaukee, Grant made his first start of the season, finishing with eight points, seven rebounds, three assists and four blocks. He scored in double-figures in seven of eight games between Nov. 7 and Nov. 20. On the season, Grant recorded three double-doubles, including a 17-point, 11-rebound effort against the Clippers on Feb. 8. In a win over Sacramento on Dec. 30, Grant posted 16 points, 11 rebounds, two assists, two steals and tied his season-high mark with five blocks.

As a rookie, Grant appeared in 65 games for the 76ers and averaged 6.3 points, 3.0 rebounds, 1.2 assists and 1.0 block in 21.2 minutes per game. The Syracuse product shot 35.2 percent from the field, 31.4 percent from three and 59.1 percent at the line. He made his NBA debut on Nov. 29 against Dallas, finishing with one rebound and one block in three minutes of action. Grant scored his first NBA points on Dec. 1 against the Spurs, when he played 13 minutes and finished with four points, three rebounds, a steal and a block. On Jan. 21, the versatile forward blocked an astounding eight shots in 25 minutes during a home loss to the Knicks. He had 16 games with two or more blocks. The 2014 second-round pick scored a season and career-high 18 points (3-5 3Pt) in a loss to Cleveland on Feb. 2. He also added seven rebounds and two assists. In a loss to the Pacers on Feb. 20, Grant went for 16 points, five rebounds, three assists and one steal. He made his first career start against the Nets on Mar. 14, finishing with eight points, four rebounds and three blocks. Grant started the final 10 games of the regular season.