SAN DIEGO (AP) — With the San Diego Padres still in deep rebuilding mode, the player a lot of fans are interested in seeing the most is a 19-year-old shortstop who has yet to spend a day in the big leagues.Fernando Tatis Jr., the son of the former major leaguer, earned an invitation to spring training with the big league club. So did some other top prospects, including second baseman Luis Arias and pitchers Cal Quantrill — also the son of a former big leaguer — Eric Lauer, Joey Lucchesi and Jacob Nix.Tatis is the crown jewel of the Padres' highly rated farm system. Once he reaches the big leagues, the organization hopes he can stop the years-long turnstile at shortstop.Manager Andy Green is looking forward to working with Tatis and other young players who will form the next waves of callups for a franchise that hasn't been to the playoffs since 2006."These are guys we've been talking about for a while and now they're here," Green said, "For me, that's exciting."Here are some things to look for when the Padres open spring training:NEW LOOK: While many of the prospects are still a year or more away from reaching the bigs, the Padres have made some additions to a squad that finished fourth in the NL West at 71-91, 33 games behind the pennant-winning Los Angeles Dodgers. Among them are the latest shortstop, Freddy Galvis, obtained in a trade with Philadelphia, and a familiar face, third baseman Chase Headley. The Padres reacquired Headley and his $13 million salary from the New York Yankees but the real score in that trade was right-hander Bryan Mitchell. The Padres then dealt Yangervis Solarte, who had been projected as the third baseman, to Toronto.ROOKIES TO WATCH: No rookies are projected to crack the starting lineup. What Padres fans are watching is the so-called next wave of young talent to come up. Tatis could make the jump in the second half of the season, although the Padres might wait until 2019 to start his service time clock. Otherwise, the next round of callups could include pitchers Quantrill, Lucchesi, Lauer or Nix.THEY'RE SET: Galvis, catcher Austin Hedges, center fielder Manuel Margot, second baseman Carlos Asuaje have spots nailed down, and the Padres really like the way left fielder Jose Pirela played last year. Clayton Richard, 34, is the presumed opening day starter, but wasn't promised much beyond that after he signed a two-year extension late last season. The Padres value Richard for his clubhouse leadership.THEY'RE NOT: Wil Myers could move from first base back to the outfield if the Padres sign Eric Hosmer, right fielder Hunter Renfroe could be back on shaky ground if he doesn't hit well and Headley may or may not be moved. Renfroe was in the first wave of young talent to arrive in September 2016 after the Padres ended their win-now experiment with high-priced veterans. But he struggled at the plate and was sent to Triple-A for a month. After being recalled on Sept. 18, he hit six homers in 11 games, including one in his first game back and had his first three-homer game. He finished with a .231 average and 140 strikeouts, with only 27 walks. Despite his nice finish, the Padres will keep a close eye on him.ON DECK: The most competition will be to fill the rotation, with a mix of young players and veterans competing for jobs. Among the young players are Dinelson Lamet, who had an impressive rookie season, and Luis Perdomo. Leading the way for the veterans is Richard, whose spot in the rotation isn't guaranteed beyond opening day. The Padres also brought back Chris Young, 38, and Tyson Ross, 30, who are longshots to make the rotation.___More MLB baseball: https://apnews.com/tags/MLBbaseball