Walden allowed one hit over five innings for the third time this season, striking out one and walking two in picking up his fourth victory of the year. He faced 18 batters before being removed. His replacement, Berl, held the SilverHawks to one hit over two frames and Avendano whiffed four of the six batters he faced.
A ninth-round pick in 2007, Walden also had similar lines on April 23 at Peoria and April 28 against Clinton -- those starts came about two weeks after the right-hander held South Bend to a pair of hits over five innings.
He'd held opposing batters to a .208 average this year and has allowed two earned runs or fewer in nine of his 12 starts this year -- he's held teams to no earned runs in six of those outings.
Walden is now 4-1 with a 2.70 ERA in his best stretch since returning from Tommy John surgery in 2009. The Fresno City Community College product missed all of the 2010 season but came back last year with Lansing, where he finished 6-6 with a 3.24 ERA in 28 outings (13 starts).
The trio out-pitched Bradley, the No. 7 overall pick in last year's Draft and the No. 2-ranked prospect in the D-backs' system. Bradley, who fell to 6-3, held the Lugnuts to one run on two hits and four walks over 5 1/3 innings, taking the loss in his second straight start. The 19-year-old has allowed 13 runs over his last three starts, spanning 19 2/3 innings, after winning five of six starts from April 21-May 19.
The game's only run came in the fourth inning when Andy Burns drew a leadoff walk and Kevin Pillar doubled to right before being thrown out at third trying to stretch it into a triple.
Berl came on to start the sixth and worked a 1-2-3 frame before surrendering his only hit an inning later when Matt Helm singled to start the seventh. Avendano struck out Chris Ellison and Niko Gallego to end the eighth and then whiffed Gerson Montilla and Matt Helm to finish off the ninth.