Contest for the Rams starting SS job?

Tevin looked at three of the biggest questions facing the St. Louis Rams during this year's training camp. Besides those issues, there will be a handful of other little issues to be settled when the pads go on next week, like the starting right guard, cornerback depth and the outside linebackers. Looking through some stats recently (and procrastinating on the TST annual) I have another question for the Rams: 

Would Craig Dahl be a better starting SS than James Butler?

Both guys have direct links to Spagnuolo from his days with the Giants. Butler, an undrafted free agent (they both are), was the starter in NY before the Rams and Spags lured him away in free agency last year. His strength has always been as an in-the-box type safety, more like an extra linebacker in many cases. 

Dahl played in 14 games last season, starting in 8 as a replacement for both James Butler and Oshiomogho Atogwe. Blue collar guys like that rarely get the credit they deserve, and while I think Dahl did an acceptable job covering for Atogwe, it was filling in for Butler where he really shined...and led me to this question in the first place. Let's look at the stats (note that these numbers come from FO's game charting and are available in both the annual and the basic online stats for individual players). 

Comparing the two in play against the run last year, using stats from Football Outsiders advanced metrics. 

Butler saw action on 35 running plays and had a 40 percent stop rate (defined as a play that stops the offense from completing a successful play, more on that here). On those plays, Butler allowed an average of 8.2 yards. It was a decline from past seasons, but how much of that decline has to do with the difference between the Rams and the Giants?

Against the run Dahl saw 23 plays, stopped 57 percent of them and allowed just 4.7 yards per play. 

Butler and Dahl's stats against the pass are very similar, with the fact that Dahl was playing free safety making the comparison a little less direct. Let's look.

Butler was targeted 27 times at an average distance of 15.8 yards beyond the line. He had a 56 percent success rate against the pass and an average of 11.9 yards per completed pass. Butler also had 7 passes defended and 3 interceptions.

Dahl was targeted 32 times at an average distance of 14.3 yards beyond the line. He had a 55 percent success rate against the pass and an average of 7.1 yards per completed pass. He had 2 PD and 0 INT. 

Those are the numbers, take them for what they're worth. It's not exactly fair to look at these and say that one safety is a better player than the other. The data does seem to suggest that they are similar players, with Dahl being younger (25 to 28) and less experienced. I'm not advocating that Dahl get the starting job over Butler either. Instead, I think that Dahl ought to have a chance to compete for the starting SS job with Butler. His play last season was a positive note in a pretty bleak year. 

At the very least, the safety position should be a reasonable solid group for the Rams with Atogwe back in the fold, Butler, Dahl and Kevin Payne.