Many of the Mariners' top prospects have already ended their Winter League pursuits, however, so it's possible Peguero is simply running out of steam.
The big youngster figures to be in the mix for Seattle's left-field job in Spring Training, where general manager Jack Zduriencik said last week that there are "a host of candidates" competing for playing time.
"It's good to hear Peguero has been playing well," Zduriencik said. "Casper Wells is feeling terrific. A lot depends on what happens with Mike Carp, whether he's the left fielder, designated hitter or a part-time left fielder, DH and first baseman."
Peguero flashed his strength with six home runs with 19 RBIs in 46 games as a rookie last season, but batted just .196 with 54 strikeouts and eight walks in 143 at-bats. He's still struggling with contact in the Dominican, where he has 55 strikeouts and 14 walks in 148 at-bats.
But the 6-foot-5, 247-pounder offers power potential the Mariners need, and it'll be interesting to see if he can improve his approach enough to earn a 25-man roster spot this coming season.
Meanwhile, most of the Mariners' top pitching prospects have been shut down, but 19-year-old Jose Campos continues to impress in a relief role for Lara in the Venezuelan League.
Campos, a 6-4 right-hander from Venezuela, has gone 3-0 with a 1.00 ERA in 18 innings over his last seven outings. Overall, he's 3-0 with a 2.63 ERA in 24 innings in 13 games, holding opponents to a .207 batting average.
Campos was a Northwest League All-Star last season for Class A Everett after going 5-5 with a 2.32 ERA in 14 starts.
Not faring so well for Lara is Yoervis Medina, a 23-year-old Venezuelan who fell to 0-7 with a 5.25 ERA after lasting just two innings in his latest start on Saturday. Medina, who is on the Mariners' 40-man roster, has made nine appearances (eight starts) for Lara and given up 21 earned runs in 36 innings, with 17 walks and 29 strikeouts.
Much of the rest of the Mariners' offseason work now is contained to the Australian Baseball League, where outfielders Denny Almonte and James McOwen were selected to represent Team World against Team Australia in the inaugural ABL All-Star Game in Perth on Dec. 21.
Almonte, 23, leads the ABL with a .382 average, thanks to a recent tear in which he's hit .486 (17-for-35) with nine runs, five doubles, four home runs and 17 RBIs in nine games for the Adelaide Bite. Almonte was Seattle's second-round Draft pick in '07, and hit .268 with 24 home runs and 97 RBIs last year for Class A High Desert.
McOwen, playing for the Perth Heat, has a seven-game hit streak during which he's batted .500 (13-for-26) to raise his season total to .367. McOwen leads the ABL with 10 stolen bases. McOwen, 26, was a sixth-round Draft pick in '07 who split time with High Desert and Double-A Jackson last year, and hit a combined .271 with 10 home runs and 53 RBIs.