1. No offense from the catchers
The Diamondbacks’ starting catcher, Chris Snyder, hit a mere .237 and only 16 homers in addition to knocking in 64 runs last year. His walks-to-strikeouts ratio—nearly 1:2—is below average.
Backup Miguel Montero has almost no power, and is only decent at hitting for average. He’s not very disciplined, either. Montero has struggled a bit behind the plate the past couple of seasons, his first years in the majors in which he's gotten decent playing time, botching 10 plays in 755 chances. He has also struggled to throw runners out, nabbing only 17-of-62 runners.
Third-string backstop James Skelton has no major league experience, and there are no star prospects at catcher in Arizona’s system.
2. Lack of outfield depth
Eric Byrnes and Alex Romero back up all three outfield positions. It won’t take much to send the Diamondbacks scrambling for some outfielders.
3. Lack of bullpen depth
Only one of Arizona’s relievers notched 10 or more saves in 2008. Another had only nine, and the leader after that had three. Using only a couple relievers/closers might work at the beginning of the season, and their durable top two starters will help the bullpen’s cause a bit. But this weakness could haunt them later in the season if they’re making a playoff push. You never want to have a vulnerable bullpen late in a close game.
4. How will the loss of Orlando Hudson affect the overall performance of the team?
Hudson had decent plate discipline, and he was a fine hitter for average in addition to being a top-notch fielder. The Diamondbacks, a team made mostly of younger players who haven’t learned much patience yet, will particularly miss Hudson’s plate discipline.
The Diamondbacks also lost their best hitter for average from last year.
While Felipe Lopez, Hudson's successor at second base, is very good in the field, Hudson was almost perfect in the infield.
Two of Hudson’s main strengths are points of weakness for the D’Backs this year. They lost a valuable asset in him.
5. Adam Dunn
Dunn carried his success from Cincinnati, where he hit 270 homers in 1087 games, over to Phoenix, where he smacked eight homers in 44 games in the later part of 2008. But, as much of a home run threat as Dunn is, can the Diamondbacks score enough runs to win in a large ballpark despite their lack of hitters who can manufacture runs?