NFL quarterbacks play in different systems with different coaches under different circumstances.

Some are going to suffer additional turnovers for reasons beyond their control.

Alex Smith would know this better than most quarterbacks after changing head coaches and offensive coordinators frequently during his first six NFL seasons.

Smith seems to be the right player in the right place at the right time lately.

The San Francisco 49ers' quarterback, credited by coaches for managing risks expertly, has not thrown an interception since a Week 12 game at Baltimore last season. He heads into the 49ers' game Sunday night against Detroit as the only player with no interceptions since that time through Week 1 (min. 100 dropbacks).

The chart, from ESPN Stats & Information, ranks these qualifying quarterbacks by lowest percentage of interceptions and would-be interceptions (passes dropped by defenders).

Smith is riding a franchise-record streak of passes without an interception. The 49ers have gone six consecutive games without a turnover. One more game and they would tie the 2010 New England Patriots for the longest streak in NFL history.

Gunther Cunningham, the Lions' defensive coordinator, says it's only a matter of time before the turnover odds even out. Smith suffered two turnovers, a lost fumble and an interception, during a 25-19 victory at Detroit last season.

The dropped interception stat is one we don't see too frequently. The Lions' Matthew Stafford has more of them since the 2011 opener (six) than any quarterback, including one against San Francisco. Matt Hasselbeck is second with four. Smith had two last season, both during a 48-3 victory against Tampa Bay.

2011 Week 13 through 2012 Week 1: Lowest INT/Dropped INT Percentages (min. 100 dropbacks)