First-half observations from Detroit's preseason opener against Cleveland:

Bentley makes risk-reward debut: Cornerback Bill Bentley's speed and instincts were on display during the first half of his NFL debut. He jumped a pair of routes, making an interception and dropping another. His position against receivers is good, but his aggressive style costs him, as he was burned for a 34-yard completion after taking a risk on Cleveland's opening drive.

Starting offense struggles when it counts: Detroit's first team left a lot to be desired during its three-series performance. Quarterback Matthew Stafford moved the unit effectively until it got into scoring position, when he threw an interception and failed to convert two third downs. Stafford finished his day going 4 for 7 for 51 yards. His performance can partly be attributed to poor blocking from the starting O-line, which allowed pressure on several plays.

D-line dominant: Tackle Corey Williams told reporters during camp that the D-line was the deepest in the league, and the unit's effort in the first half proved him right. The front four kept Browns' quarterbacks under pressure, and DE Willie Young continued his impressive play by making a sack-fumble that ended the first drive. Detroit had three sacks in the first half.

RB Williams has impressive half: Running back Keiland Williams' first-half effort may be one of the biggest positives of the opener. After struggling last season when he gained just 195 yards on 58 carries, Williams rushed for 69 yards on eight carries (8.6 ypc) against the Browns before being replaced by Joique Bell. Williams' combination of power and speed is something the Lions sorely missed in 2011. If he continues to run the ball well, Williams can help alleviate major backfield depth concerns.

Follow Lions reporter John Kreger on Twitter at @CBSSportsNFLDET and @JohnKreger.