- Bats Left, Throws Right
- Height 6' 1", Weight 200 lb.
He debuted in the Extraliga with the Arrows Ostrava in 2010, going 5 for 19 with a walk, fielding .824 and posting a 0-1, 5.79 record on the hill. In 2011, he allowed 3 runs in 3 innings and did not bat. He participated in the MLB European Academy that year. In the 2011 European Junior Championship, he was 1 for 6 on offense and struggled on the mound (3 R in 1/3 IP). He became a regular in 2012 for Ostrava, hitting .290/.321/.542 with 6 homers and 22 runs in 30 games. He did not pitch (21 R, 15 ER in 9 IP) or field (.875) well. He tied for 5th in the Extraliga in dingers.
Junec moved to first base in 2013 and stopped pitching. He batted .346/.352/.394 and fielded .972, then was 1 for 12 with three walks in the postseason. He did not homer in 26 regular season games after having made the top 10 in homers. In '14, he hit .311/.401/.361 with 28 runs in 35 games, fielding .989 and was again homerless. He batted .320/.452/.360 with 7 runs in 5 postseason games. In the 2014 European U21 Championship, he was 10 for 15 with 3 doubles, a walk, 9 RBI and 8 runs in four games, leading the event in average and slugging, finishing second in OBP, tying for second in doubles and hits and finishing second in total bases. He did not win the MVP, which went to teammate Adam Hajtmar. He hit .371/.421/.400 with 6 RBI in 9 games for the 2014 World U23 Championship, finishing second on the Czech team in RBI. He was named the best young player in the Extraliga in 2014.
In 2015, he hit .370/.410/.603 with 32 runs and 28 RBI in 35 games. After two consecutive seasons without a dinger, he went deep seven times. He was among the Extraliga's leaders in hits (54, 3rd, behind Corey Lyon and Daniel Vavruša), tied Jirí Marek, Jakub Voják and Mitch Nilsson for 5th in doubles (11), tied for 6th in home runs, tied Matej Hejma for 4th in total bases (88), was 10th in runs and led in putouts (275). His postseason batting line was .261/.346/.565 and he tied Petr Cech and Jakub Sládek for 7th in RBI (7).
Junec made his debut for the Czech senior national team in the 2017 World Baseball Classic Qualifiers in March 2016 at age 22; he was the team's second-youngest position player as only Adam Hajtmar was younger. He pinch-hit twice. In the opening 2-1 loss to Mexico, he batted for Michal Ondrácek in the top of the 8th with one out and fanned against Jake Sanchez. In the semifinals against Nicaragua, he came up in the clutch, down 7-6 in the bottom of the 11th with men on the corners and one out, but he struck out versus José Luis Sáenz.