Bello was promoted to Triple-A Worcester on Monday, Chris Cotillo of The Springfield Republican reports.
Bello is one of Boston's more interesting pitching prospects. The 22-year-old righty impressed in six starts for Double-A Portland to begin the season, striking out 32.6 percent of opposing batters en route to a 1.60 ERA. If he continues to impress at the Triple-A level, it's possible he gets the chance to make his big-league debut later this season.